Welcome, and sorry to hear about your troubles. Judging by the retaining straps I'm guessing your van was supplied by Leisure First in Dorset. I'd advise giving them a call as it will still be under warranty. It is probably a matter of a simple adjustment, but for you to get the lockers open you could damage the surface finish on them. You could try a plastic bladed spatula or pallet knife to free the latch. If this works spray some ptfe spray into the spring part incase it is sticky and not releasing. I adjusted one of my latches by removing the catch plate and packing it out with a couple of washers, but I think you have the opposite problem to what I had. I suspect if you loosen the catch on the back of the latch you will find some adjustment. You only need a mm or so.
On a positive note, it looks like your van has far better hinges fitted than recent vans. They look bigger and have a surface treatment that hopefully will not tarnish/corrode. I doubt they have deformed under the weight of the locker hatch as they look fairly robust and the hatch is surprisingly light.

Colin