MTN triple invoices a Customer for no reason

It is amazing how bad the service with MTN has been so far. The only person that is try her best is the sales person. MTN itself has severely terrible services. First i get a SIM card that does not work and has said ricabarred since i got it this month. Then suddenly on the 20th of December 2018 i notice an additional charge or PSD Calls and and over charge of nearly R2000 for a SIM card that only started working on the 20th December 2018. Well now, i would class that a extremely terrible service from MTN itself. How can i have an account opened and suddenly over charges appear for no reason. They just there. I waited not only for nearly 3 weeks to get a working SIM, but when i got it, i was being overcharged by nearly R2000 for something i have not even done, when there is something like 131 Gigs available on it when i checked that same day. Seems as if MTN is trying to scoop extra money from the public thinking we won't notice the added amounts. It is crazy. There is no ways i will let MTN debit my account for an invoice nearly triple the invoice amount it should be, when i have in no way over used it when it has over 100 plus gigs on it. I think this is absolutely terrible of MTN to do this nefarious things towards their clients.