BAD SERVICE AND COMMUNICATION FROM RCS CARDS

I have a Game Personal Loan and paid by Debit Order. Every month they send me a sms saying that my account is in arrears. I Phoned, email them without any joy. I once of twice sent back the debitorder and paid in cash directly into the account. Today again they send a sms saying that I am in arrears. I am afraid that this behavior will reflect badly on my credit record. DO THEY HAVE ANY SYSTEM??