Paid up Letter

I have been trying to get a paid up letter since I made an overpayment on a settlement amount on 28 April 2023. I have sent numerous emails to MBD's ***, various consultants and have made numerous calls to try and get a refund (which they confirmed) and a paid up letter. I get no response at all. MBD will call you a MILLION times to settle with them ASAP - they even sent me the settlement letter the same day I spoke to them BUT the paid up letter is locked up in a fortress somewhere, where they only know. Maybe this is how they operate because its their standard practice - to hold us ransom for as long as they can. Or else why would everyone be struggling to get a paid up letter. I wonder how many paid up letters they have issued to clients? I wonder how long is has taken them to do that after clients had paid???? Something needs to be done. They need to be reported to a higher body.