Sham of a company

I had an account with MTN which was handed to this company. Subsequent to that, I made a payment for the outstanding amount owed to MTN and sent through my proof of payment to them.

I still have not had anyone get back to me confirming receipt and explaining to process, given the phone call that I have made, that is to follow given the fact that this account has been listed on my credit report.

I am yet seeking assistance with confirmation of receipt of my payment so that my credit score can be updated accordingly as it is not, I will be making sure this company gets all the attention it's clearly looking for not handling this matter.