Never answers either phone or email
Never answers either phone or email, and is never anyone in the onsite office to deal with a query. There is no way get a quote out of them, so goodness knows what the customer service is like.
Doesn't look like the site has a toilet, so you would need to pack everything away and drive the half mile to Morrisons. Or use a bucket inside your container, and empty it by the fence.
The road you have to use to get to the site is one vehicle wide, with a nasty blind bend. Don't attempt it at peak times because those who work on the other sites there will just blindly plow into you
