Bad, bad service again!

I have had a data/sms/call deal for quite some time that I did not want to upgrade because it took me months to get MTN to debit the correct amount for the deal advertised in their catalog at that stage. And then I did it - I upgraded and here we go again!! I complained because I was debited with R76 too much the first month. (The deal is R199) After struggling via Facebook Messenger and Twitter to resolve my query, an sms was sent to my daughter's phone? yesterday telling me I have a credit note for R177.42. BUT this amount of R177.42 is now reflecting on my MTN app as being outstanding? No-one replies to my messages and I am am rather upset at this stage and is seriously considering getting a stop order and cancelling the contract.