just been getting quotes for a van and there pretty cheap but when i add water tank to the insurance it says ring them up. i rang a few companies up and they want an extra 100-190 quid just for a water tank. is this right?? i didnt think it would cost that much more.. so if i wanted to get warm water system id have to call them and say ello i got a gas bottle in the back for them to wack another 300 ontop.