Paid but receiving arrear communication.

Disgusted at the level of service from Cell C. I have made a payment using the Cell C App.. I have been receiving countless messages that my account is in arrears. I called and the agent I had spoken to initially said they could see my payment and that I should ignore the text messages. The messages continued with emails as well and an adverse on my account. My issue is why make the option to pay via the Cell App available if you do not recognize payments made via the app?? How do we solve the issue with the slow payer status on my credit record? The agents are also not willing to assist with the allocation of payment and you hear different stories each time you call.