LGR Attorneys / Std Bank ****

Despite the fact that our Standard Bank credit card is not in arrears, we have been receiving threatening sms's from LGR Attorneys. We have provided proof of the fact that we are not in arrears by sending them a copy of our bank statement. I am very concerned now, is this a ****? We were required to sign a special Power of Attorney, which we did and sent to them but have had no response. Why do they keep harassing us?