Insect mystery in new caravan

Hello,

So, the time has finally arrived - we are a few days from picking up our new caravan. Becuase we want to go straight from picking it up to stay somewhere overnight, I drove the 1hr30 round-trip to put some stuff like duvets etc. in there in advance. 

I was given the keys and saw that the caravan had been prepped, and was really chuffed but as soon as I got inside, the chuffedness turned to concern and itchiness.

The upper bunk had a variety of different insects on the mattress, concentrated under the skylight area, all dead.

Mostly, they wer gnat-type insents, some absolutely tiny, but there were a few small black beetles too and tiny yellow spidery looking things. Probably well over 100 in all.

Yuck.

We went to find the salesman who said that the vent must have been opened when they were cleaning, but in any event, they could have got in because of the ventilation system in the caravan. This does not seem to me likely but I thought I would seek your experienced opinions.

I can't think it normal for dozens of insects to fall through in a period of three weeks or so (when we last saw the caravan and the mattress protectors were on. 

I said to him that if the skylights had been open, they were now closed, and why did nobody do anything about the insects.

There are a few insects in the bathroom under the skylight area too.

My main theory, and bigger concern, is that the skylights have been left open and the caravan roof washed. This would explain why there are so many insects, and why they are all dead. There weren't any on the kitchen worktops etc.

I am really disappointed - a new caravan is supposed to make you feel warm and cosy, not itchy! I queried replacing the mattress and was toldthat this would take 12wks, and there is nothing actually wrong with the mattress.

However, I am minded to think that the fault lies with the dealer and I am concerned about my water theory for damp reasons, but also if any insects did come in alive, whether they have laid eggs in the mattress - yikes!

I am told a mattress would take 12wks. I am minded to take the caravan, use a waterproof mattress protector, hope we don't have a damp issue but insist the mattress is changed.

Sorry for this long post, but I hope to draw on your collective wisdom. Thank you.