Vodacom Very Very Poor Service

I have paid my December 2020 invoice on 30 December 2020 through the MyVodacom app, it went through my bank on 2 January 2021.

Now I keep getting calls and messages telling me that my account is in arrears.

I have sent mails to 4 email accounts that I got from Vodacom numerous times, they are still not allocating my payment. They keep on calling me and it is frustrating.

What am I to do next? Is cancelling contracts an option as this is not my fault that Vodacom does not allocate my payment?