Unknown spillage in the boot.

I recently took the Octy into my local Skoda dealership for it's for first service. They kindly identified a nail in the rear offside tyre.

A couple of days later I dropped into an F1 Auto Centre to remove and repair it, when I popped the boot floor up to get my hockey puck jack pad and locking wheel nut key I noticed the carpet had come away from the board - when I looked underneath the board was partially covered in a waxy stain (see pic)

Whatever has been spilt in there has removed the adhesive which holds the carpet to the card.

I popped called the dealership that day and popped back today (this was the earliest I could manage to get down there), helpfully the service manager has tried using a spray adhesive to stick it back down, I don't believe this is working though as the carpet appears to still be loose. He has said if it doesn't work - come back and they'll sort something out.

The service manager has said it smells like coolant, I do have some coolant in the boot, but it's in the styrene spare wheel holder underneath the boot floor - so if this had leaked it would leak down into the styrene. As there is about 100 ml of coolant gone out of the entire bottle I don't believe this is the cause.

The service manager has said the service engineer has no need to go into the boot, but I kindly pointed out that they checked the expiry date on the can of tyre weld - so someone must have been in the boot.

What should I do - have them replace the boot floor or allow them to fix the issue? I can't honestly prove it was them, as they can't prove it wasn't - so it's my word against theirs, but they seem really helpful and willing to sort something out.

If I could remove the chemical out of the card, it would stick. Should I try and fix it? is it even possible to fix?

Any advice would be appreciated.