complain

I had a contract with Mtn and after loosing my job the account was handed over to HammondPole attorneys, I managed to pay the account through the attorney and on the 4th October 2019 I settled the account and received a settlement letter. 2020 April i started receiving calls and smses from Mbd saying that i have an outstanding account with mtn, i've sent proof to them and have been contacting mtn legal about this issue with no luck and it has been two months of sending emails to mtn legal with no luck.