Poor customer service and ****** customer funds

I have tried to escalate my issue with someone higher when I phone in to the call centres however everyone says that I just have to wait. I took out an mtn contract with the mtn store at the atrium branch in Durban. I cancelled the contract within 3 days and I never took a delivery of the device either. Apparently mtn did a partial cancellation and debited me an amount of R5841.64 on the 30 October 2017. I have contacted the branch and the 808 number and I was told that it was a mistake and I will be refunded within 7 days. Thereafter ever since that date I have made numerous amount of calls and I am still told I have to wait as the money is sitting in my mtn account and needs to be sent to my fnb. They have all my details and I can't understand why my refund is taking so long as I really have indebted myself as the amount that was taken out of my account has made my account go into overdraft and I even started using my credit card as I had bills to pay and a family to feed. I tried to escalate the matter however I was told there is no higher management that I can speak to and that I have to wait. I have ref numbers for all my calls. I even asked for their banking departments number so I can speak to them about sending the money to my fnb account sooner as I have been waiting many "7days" since the date of incorrect debit and I was told they don't have a number to call, they only deal via email. I am so frustrated at this point and disappointed with mtn as I can get no further help from upper management whilst it was no error of mine.