I recently upgraded ...

I recently upgraded my contract and a new debit order of 1600 was supposed to be debited but they debit 12000 imagine FNB was so kind to reverse the 9000 but the remaining could not be reversed due to a block that MTN added to the debit order now they telling me I'll only get my money back after 3 to 5 working days what am I supposed to do without money in the meantime