If anyone could advise I'd appreciate it...

I instructed a merchant to commence a direct debit recently. Since then I have

received notification from the merchant's bill agent that the direct debit was rejected

by my bank and subsequently charged back.

The billing agent is now invoicing me for the original debit amount (fair enough),

plus the same amount in chargeback incurred and an administration fee.

The banking details I've provided were acurate and I've not spoken to my bank to

ask about the rejection.

Under any circumstance, am I liable to pay the chargeback or is that their problem?