Mtn taking our hard earned money!!!!!

Mtn taking money from loyal customers. last month i received an sms saying there is a billing issue. i paid R720 last month. my monthly subscription is R850 pm. insurance included. this month i received an sms debit order for R1299. its R450 more. i called mtn they said its because of the billing error. R850-R720 is a difference of R130. not R450. after i told the lady to so her sums she said my insurance billed me double. without a letter from them explaining why. so they took R320 without letting me know. She said insurance is now out sourced and she cant help we. i want to know how they can take our money? i am due for an upgrade from tomorrow. but i wont deal with a company thats taking our hard earned money. that is not good service mtn. i want my contract to be cancelled asap. i have enough influance on a number of people to tell them not to use mtn anymore. poor poor service. good bey mtn. hello cell c. the network that really cares!!!!!!!!!!