TRS recovery services tried to get $2500 saying my western union money transaction didn't go through. but WU said they are fraud. houston, Texas

I made a money transfer transaction in WU a while ago. 4 months later, TRS sent this mail that said my payment to WU did not go through, but the money was still picked up by somebody. So I have to pay back this $2500, this time to TRS. They had my name, address, last 4 digits of my bank acct, the date of transaction, the amount of transaction. Everything was correct, so I couldn't think they were fraud. I checked bank account, and the money was withdrawed on time, so contacted WU. they said everything is cleared. And NO ONE knew about TRS company, even manager. After a few transfers, finally ended up talking to head manager. She said I'd better change the account number or close the account, since this company is fraud.