Default payment history whereas they are paid

Few months ago I missed a debit order, but immediately after receiving an sms about same I called Vodacom and I was told that I can pay it via my bank app, which I did. Few days later I checked my credit profile only to see a default payment has been made on my name. When I called Vodacom I was told that it will be updated in two weeks ago. Today I checked it and it still not updated. I decided to call only to be told that I missed a payment for August hence the default, but the agent also confirmed that I made the cash payment on the 31st of the same month. Trying to reason with the agent I was told am speaking alone and I wondered how a person am speaking to can say am speaking alone. I asked her as to who is lying between herself and her colleague, she ducked my question and not answered same. Requested to speak to the line manager, was told I can't speak to the line manager, will have to wait for an hour. Don't know who to believe now and where to go because the account department can't assist me. Just checked my credit profile only to realiaed that it was not for the first time but twice they are doing this to me.