Vodacom Bill inconsistency

Last year July, I bought an iPhone 11 at Incredible with the Vodacom contract. On the 3rd of July I called Vodacom for them to set the credit control on my phone to be R0, so after the minutes for calling and everything has exhausted, I wouldn’t be able to make any calls. The lady I spoke to set the credit limit and I got a confirmation sms after that. However the bill kept going up and down until I went to incredible connection so I can call Vodacom. When I call they tell me that NO credit limit had been set ! And I do not understand because I spoke to a lady on the 3rd and she set it for me. The lady also I spoke to as of recent told me that they will get audio recordings of that call and get back to me but she has ALSO not fulfilled her promise. Till today I still await and there is nothing! I am absolutely fed up with your service ! I have the screenshots confirming the fact that a credit limit was set.