Fade up with MTN

l am done with MTN,i have been paying my account and they never allocated my payments since September 2019 and in December i was surprised that my account has been handed over to Hammond Pole attorneys. I did sent them all my proof of payments so many times but still nothing has been done by both MTN and Hammond Pole Attorneys. I have been calling the attorneys so many times and cant get hold of anyone to sort my account all they told me was we cannot allocate the payments done before the account was handed over to us. So who is going to allocate my payments and am not going to pay twice the account where did mtn allocate my money. i know that am in arrears for less than a thousand rand but they sent me a letter for 17K and another statement for 6k honestly am fade up. Now mtn and the attorneys have messed up my account and my credit record yet payments were made every month. Please Please help me .i dont know where to go now noone is looking at my proof of payments they just want me to make a payment arrangement of what yet l have been paying. I also sent my proof of payments to the mtn customer care but still no reply