Discount offer

I was offered a 30 percent discount and i accepted it. Of which i had pay for 3months and i honoured the Agreement but now that discount has been brought forward as a remaining balance and now MBD doesn't wanna remove the mandate for the debicheck and don't want to close the account and should it deduct this month am reporting MBD for bridge of contract. I have been calling from end of march till this day. And am being told that the matter has been escalated and that i should make sure that the debit order doesn't go through mxm