GFK 

This company is a SCAM!!! they calling from a local number and ask about a credit card processor, I guess they tried to sell me one.
Blocked there number and report
complaints.donotcall.gov

Used this survey company for months and at the beginning I used some of my points to enter prize draws. Didn't win anything but would occasionally recieve £1 or £2 to exchange for vouchers etc. Not much byt nit bad for a quick survey. Then it got less and less, maybe a £1 every 2 months and all of a sudden cant access any other part of the website to use my 100,000 points!! Have sent 7 emails now and recieved 2 back both saying they can see I've now resolved my problem. No I haven't you morons!!! Avoid at all costs I've literally wasted hours for nothing and I'm furious. Have also complained to the bbc as it seems to be run for them but nothing back yet which doesn't suprise me!

GFK is the reason spam filters exist and why you don't want to give out any of your data to companies.

Been doing this for about 18months or more and only won about £12 and that was a long while ago. Enter draws regularly and still no winnings. I am stopping these surveys as it is a waste of time.

Don’t waste your time!
Can’t unsubscribe no response to email.
Everything as stated from other comments
They sell your data too as now I get random
Calls from health insurance and accident .

Never respond to email support for requested vouchers. Cannot unsubscribe have now had to mark their emails as junk. Just don't bother with this company.

I was hired to conduct research for this company. I was sent a cashiers check and asked to complete assignments. As soon as the funds cleared my banked, I completed my assignments and sent proof. As soon as I sent proof, they reported my payment as fraud and the funds were withdrawn from my account. I am a single mother who is now out $1,000. I don't know how I am going to make ends meet this month due to their unethical practices.

I have supposedly been awarded several rewards from the TV review but they never arrive in my email box. Having contacted them several times and received no answer whatsoever I have decided to contact the BBC, because I believe that is the company they are contracted to for their surveys. If anyone else wishes to do so, there is the BBC website page with information on how to contact the BBC online, by post or phone. I can't give you the link here but it's easy to google.

Don't waste your time. I have been doing surveys for over 6 months and not won any of the prizes. Its a con. They make money but they don't reward you. I have emailed GFK 4 times now to complain. Absolutely no response so I have stopped doing the surveys. They are the ones who benefit so don't waste your time signing up and doing the surveys every day. They are cheats and don't care about the panel members.

I signed up to GFK months ago and faithfully filled out the survey every day. After a few months had passed I realised that I wasn't getting the monthly emails with my balance, so I sent a message through their 'contact us' form. A couple of weeks later, I still hadn't heard anything, so I tried again. And again. And again...I've contacted them five or six times now and never received so much as an acknowledgement, never mind actual help. This company is not worth your time. Sign up with someone else.

terrible company. I religiously complete their tv and radio survey, but they have not completed any prize draws since October. Avoid at all costs.

gfk use to be digital trends they paid for firsat few months then stopped paying me, they then changed name to gfk digital trends payed me for first few months, then stopped alltogether. dont use this company they will just rip u off and stop paying u. also the survey with gfk trends they stopped paying for them..they are worldwide company which treat users like crap, stay away from this company, i hope the truth gets out there about this company another which treats survey takers like crap, they are not the only ones.

TBH I've done surveys with this company online and through focus froups and got paid £50 for maybe an hour or so focus group.
They aren't that bad.
My experience with the TV and Radio is the same as others. It's gone completely downhill.
It's now a waste of time.
The points are worth nothing, if you receive them at all.
It's a completely broken model.
That's the reason I give them the rating I do.
I know they do valuable research in other areas.
This is just bringing their reputation down.
I f they're not taking it seriously they should just close it down.

Really bad system. Answer questions daily for no reward just some draw that hardly gets updated! Waste of time if no reward!

Although I have received the odd voucher in the past from GFK. This year 2017 they don't appear to actually do the draws they claim to do every week. It's now almost Christmas and there results page shows results up to September. They apparently had a draw for £1000s but the points draw also shows no results but I've seen adverts from them saying they pay up to £1000, clearly they don't. I have used their 'contact us' but they don't reply to any requests. We are all being conned by this company. We do all their work for them for which they no doubt get paid a great deal and we get nothing in return. They should be forced to close down.
.

Only been doing the radio and TV reviews for a month but as stated elsewhere ...

double points don't happen
Extra points are either less than promised or don't happen
no response to multiple emails

Best to avoid to save wasting your time

DO NOT GIVE YOUR DETAILS
These are a total con, they play havoc with your tech, and you get £1 par month in rewards, even though they promise £10 per item with gfk digital trends app installed
Then they ignore emails, and cannot be contacted by phone

Don’t sign up. I’ve sent repeated messages asking to Unsubscribe but that has been ignored. Very annoying.

I would offer no stars at all if that was an option. Sign up and you will never receive the vouchers/rewards promised but you WILL get an endless stream of emails.

Avoid like the plague

Can't uninstall app for Gfk
Having downloaded the app some years ago I got fed up with its start up screen interrupting my online searches so decided to uninstall. Cant be done on Windows 10. GfK supplied a program to do so. Doesnt work.
Beware