I had a very similar situation, only I drove up to Northampton in my elderly motor to collect said vinyl tiles (they wanted silly-much for delivery). It was about a quarter of a ton so sounds a similar quantity, which made the handling a bit interesting, but I reckoned it was about the same as having a car full of rugby players. The back axle survived the trip down the M1/M25/A3.
They were 2.4kg each and strapped together in bundles of ten, making a 24kg bundle. Which was heavy, but not unmanageable. Shifting ten bundles doesn't sound too time consuming.
Doing this for 4 tons of tiles sounds like a PITA, but possibly easier than faffing around with contraptions. If the seller doesn't come suitably equipped to deliver, they should not be surprised that it's going to take longer to unload.
Good to know. I bought some of their cheapest shelving and it was useless (thin steelwork and hardboard, wobbled all over the place), but I suppose you get what you pay for.
Theo