Welcome to the forums.
You are the third person in recent memory to write here on the forums that their bank transfer has not yet shown up on their account after a similar amount of time.
I really don’t know why this is. In the past I have quoted Google writing that bank transfers can take 5 working days, there has been a weekend, so there is a chance that your funds arrived at Prolific two days ago.
In any event, it is not only you, others have found that bank transfers can take a long time.
Also, till very recently Prolific had a notice saying that over the end/beginning of their year there would be less support (there is quite a generous benefits package at Prolific allowing for quite a lot of holiday) so the accounts department may be overwhelmed.
There is normally, or according to a Prolific FAQ at least, a small charge should you wish to be reimbursed. But perhaps that may be either legally contestable and or waived in this case. If so, or in any e vent, you may consider using a credit card. I find that if I use my credit card (I have never tried a bank transfer) the funds show in my account almost immediately.
I am sorry I can’t be of more help,