FURIOUS - No time on refund?!?!

So I was Debited WAY too much this month. I called on 01/08/2018 and requested a refund, to which they said it would take 48hours. Today is the 13/08/2018, after numerous calls, no refunds have been processed, and all I am told is they cannot give a time, I just have to wait. My bank account used for my payments is currently in the minus because of MTN, IF FNB have to dishonor me for MTNs' mistake, MTN can expect their hubs to be burnt down to the ground. I expect Credit management to get a hold of me ASAP!!!