Supossed Buy-1Get1-free cellphone dael, cost me over R1400 and query not being resolved

I have been offered a buy one get one free cellphone deal with my last upgrade, but when I got my bill last month I was charged an additional 700 for the cellphone that was supposed to have been free. MTN investigated and confirmed this is incorrect and they logged a ticket last week Wednesday. On Sunday evening I got an sms stating the ticket it closed, yet today my account was deducted again with an additional 700. Then I tried calling the MTN customer call centre and they said sorry they need to re log the ticket. This after I had spoken to 3 consultants who informed me they were offline on their side. This is shocking service.