Loyal customer being treated like a dog

For the past few months I have had non stop issues with my MTN debit order, after being a client for roughly 8 years. Every month they either debit early or not at all and then my credit score is negatively affected because of unpaids, I have called every month and each time the agent tells me they can't see a problem, today an agent told me they changed systems 3 months ago and have been having issues with billing, so I must be negatively affected because MTN decided to change systems and not implement properly. The agent also said even though the unpaids affect me negatively its" proberly not that bad". REALLY??? AS SOON AS I CAN GET OUT OF MY CONTRACT, BYE BYE MTN. This is not how you treat loyal customers of almost a decade with 2 contracts. Agents name is Khensani, Ref ***, oh and when I asked for a supervisor I was told because they are working from home I cannot speak to one, great service, and by the way your IVR says service champions??? I think not