Talk very promptly with your local Trading Standards to get your full money refunded under the new very powerful version of the Sale of Goods Act. You need to act with the dealer using the right approach and Trading Standards will advise you. Time is important. Don't be seduced into a repair as you say the van is purchased as new.
Then buy a make not known to crack in this way or have other totally unacceptable build failings.
The sooner the dealers wake up to the implications of selling defective goods, particularly in our leisure industry, and put the pressure on the builders then the quicker we can hope to be able to buy goods fit for purpose.