Debit Order Dis-approval

I have a challenge of MBD forcing me to pay my account with debit order even though I am explaining to them I don't have enough funds in my account because I am afraid that the debit order will not get funds/money in the account and if the debit order bounce the bank it's charging me and one other thing is that if they don't get money they are tracking the more they track the more the bank charge me I end up paying lot of money. So they want to go through with it even I explain to and I dint approve at the Bank. Regards Sarah