Deteriorating service after good review

It was not long ago that I wrote a review on the exceptional service I received from an individual of this organisation but since then, it has been a complete decline. This individual migrated me to help save some money, but unfortunately crippled my voice minutes, I was then migrated 3 more times to fix this and then finally got it and was able to use my device. I was offered complimentary months for the inconvenience and issues that I had faced. I saw this in my December invoice which was R0. A few days later I was debited R645. When I enquired, no one could trace the invoice nor give me any answers. I logged a call and was told it will be resolved in 24-48 hours, its been more than a week and I have called in only to be told nothing can be done. I have further now received another invoice which should have been R0 but is about R400 and something. This is unacceptable, the agent offered me compensation for a issues and now no one can even find the person on the system. I am deeply saddened by this attitude. That's the issue with complimenting people, they take it for granted and never show you the same good service again.