Banking Details

Can anyone please advise me, I have been given the run around by the finance department for the last 4 months.

Last year I appointed a managing agent for my property payments from Booking.com where made to thier account. Since then I have taken back management of the property when I tried to enter my Bank details they where rejected as my account is based in Belgium and not Slovenia where the property is based. I was told that I could not use this account as with the Booking.com payment collection. So I said OK in that case I will revert to collecting payment myself. Asked them to remove the old Banking details from the system as it is no longer current and not my account and further more not needed as Booking.com are no longer collecting payments on my behalf. I am unable to delete the details my self every time I try to do so the old account details reappear. I have been asking the finance department to do this but they say they cannot, so I am in a situation where Booking.com are holding false out of date information and refusing to do anything about it,I find it hard to believe that no one in the IT department can correct this. I feel like I am hitting my head against a brick wall trying to solve what should be a simple process.