Account not billed properly

Ive been complaining about this for months,no MTN consultant can pick up that there is any wasp services added on the account,but every single time i fill in airtime it gets eaten up.i have a data package that does decrease when i use Facebook and internet. There was a credit passed on the account which i was told but has not been emailed to me as proof that it was done. I am not going to complain again. the next step is going legal.Ive been understanding up till now. you are a big company but your phone lines cut calls off every single time.I know about the call volumes but not calls getting cut every time.