Poor Service MTN Eastgate Entrance 4

MTN Eastgate Entrance 4 next to checkers entrance has pathetic service.l upgraded my contract end of August where l picked up a Vivo for R299 a month but the guy who processed the contract gave me a Vivo e27 which was R169 more and never told me or give me an invoice to sign .I was promised it will be sent to me till to date nothing has been received.I went and queried this was told l signed a contract should have seen the amount and honestly l did not and got home did not find the copy of the contract.Every month since l took the contract it's a different amount being debited in my account R563.74 debited first month was told debit order is R469 plus prorata this morning R609.01 debited what nonsense is this.Need this resolved cannot go to your branch at Eastgate where l got the phone coz their service is very bad even the person who was assistant Manager that day took my details and said they will call nothing to date.This can not continue otherwise take your phone back and stop messing around with my account otherwise l reverse this whole amount as it was not in my budget and hate surprises with my debit orders.