Vinted complaint: Didn’t pay me my earnings

Sold a dress for £25. The buyer received the dress and left positive feedback. Money went into my vinted balance. Then came the issue… withdrew the £25 balance to my bank account and was told it would reach my bank no later than 28.12.23. However over a month later and I still haven’t received my money.
I contacted vinted multiple times over this and provided my bank statements (that they asked for) as proof the money didn’t reach my account. I was then told that I would need a signed letter from my banks manager saying that the money didn’t reach my account (seriously??). So I first phoned my bank branch (I’ve done this 4 times) and was told that this isn’t something they would ever do, and that a bank statement should be enough proof. I informed vinted of this, yet they still insisted on a signed letter. So off I went to my bankin person, and was also told by 2 members of staff that this isn’t something they can do. I printed off a copy of my bank statements in branch and was told by the manager that that was all the proof I should need. Again, vinted wouldn’t accept that
They have now basically ignored any message I have sent asking to be paid my money, and have said without this magical signed letter (that Lloyd’s bank say they have never done) they won’t help me with this issue
Vinted are thieves