Line blocked for no reason

On the 14th of December I paid my account using a credit card on the CellC App. On the 24th my line was blocked. After numerous calls and emails I was told that I need to forward my proof of payment. I paid using my credit card on their app. The system does not give a proof of payment. Then they said they see I'm having trouble making payment and I should EFT. I've paid already! Then I made second payment. Now they need to call me and telephonicaly verify it's me. When they call the line is just quiet and eventually they hang up and email me telling me they tried to call me. It's been a week now without being able to call. I'm in tourism and this is my busiest time of the year. I'm stuck without being able to call and arrange my work. I often but SIM cards for my clients and spend R5-6k on CellC per month. I will not be using CellC in the future.