Poor service, wrong billing

I app**** for a R199.00 black Friday data contract special at northgate mall mtn. I got a call saying the deal was approved, when I went to fetch the sim card I was told that they processed the wrong deal at R299.00. I asked for them to correct this on the system as I will not accept the wrong deal and it was not my fault. This was on the 27th of November. Till today the ****s are still fixing the deal on the system. Today (27th December) my bank account was debited for R428 by mtn. When I called mtn I was advised that it is for a R299 data contract + pro rata billing and bare in mind I do not have this sim card. When I called mtn northgate they told me that when mtn approved the deal they activated the contract on the system and they were fully aware of this but chose not to tell me. I want the money returned to my bank account by cob today, the R299 deal deactivated and the R199.00 black Friday deal activated on the system. I will be reporting this matter to the ombudsmen. ****ing ****s !!!!