They answered me an hour ago, they just sent me an email asking if I wanted a refund or a replacement. I called to avoid further delays and the response was something like:
"Are you sure that the plastic foil is still on the pickguard? The signs could have been caused by the QC here. Ah, there was no QC... so the bass probably has those marks because of the QC in Fender. No, we cannot check every bass that we ship to be sure that it is new. A refund is better than a replacement in your case. We will send you a prepaid UPS to pick the bass at your door. Goodbye".
It was fast and efficient, but not a single "we are sorry", not even a fake or courtesy one. But probably it is just me that I care about the customer care.
Obviously they didn't offer me any kind of compensation, I think that it is cheaper for them to just resell the bass as brand new to the next less-picky customer, I really don't know.
I wanted to reply to the people here saying that the thread was unnecessary, that I am overdramatic by losing faith in this retailer or that I am judging (??!) an entire mega-company by a single episode, but... well, I think that now it is irrelevant.
By the way: what's the best solution to get a fender jazz deluxe here in the UK? Any trusted retailer?