Disgusting MTN

I have a 80gig (40 day/40 night) data contract with MTN and have had no issues for the first 12 months of the contract but since October 2020 suddenly the data is not correct. MTN clearly states that unused data is carried over to the next month for 60 days only. The unused night time data for the past two months is just taken away. I have been trying to resolve this with their consultants but I am told every time that the matter has been escalated (new name for, forget it you will get nowhere). It is not a complicated matter and I do not have to continually phone them to clarify the matter. I have been a customer of MTN for the past 17/18 years but I think that it will come to an end once my contract expires in September 2021.