ADT Security. Accounts Department

My complaint is only with the accounts department. I paid an amount in August 2024 by EFT and the same amount was taken off later by debit order. This error was mine. The original amount was share by two people. I requested that they reimburse me. They asked for the 2 proofs of payment, which I sent. On the 23rd of October they finally paid me half of the amount. I asked them to repay the 2nd half and they again asked for the proof of payment resent both again. I received nothing. I tried to get hold of them by phone but the people answering s were unable to get any answer from the accounts department. IO mailed them again and was told that the money had been paid into an incorrect account and was being corrected. Another week has gone past and even telling them that I was going to post a complaint has not produced a refund. I have no problem with the response time of ADT, but it is now 3 months and I still have not been fully reimbursed