unpaid visa debit card transactions!!!

i am new to this posting so stay with me on this:

I am a business owner and about 4 weeks ago i got 43 returned visa debit card transaction, of which 42 had cash back, to final total of just over €6000. all transactions are from a local customer who frequent my business daily if not twice daily for the last number of years. and is friendly with all staff members. anyaway i copied and sent the pin verified merchant copies to the charge back section of merchant services as proof as requested by them. 2 weeks later they said i would not be refunded my money as there was a "forced Authorisation" on these transactions. I investigated into this to find out the customer card was not working properly and she told the staff members that she had been in contact with her bank and just enter 1234 as authorisation code and transation proceeded as normal. when i informed her bank of this, they said there was no money in her account to meet these transactions at those times and this was not there problem as authorisation code entered by staff was not got from bank. what bothers me is that when i trialled my card with no money in my account it said transation declined and no option for authorisation code, but with this customers card that did not happen, it came up as delined refferal, which led to authorisation code to be entered. is the card issuer (the bank) anyway responisble for allowing this card to keep continuing without notifying my business and also allowing her cardholder to enter the authorisation code. What can i do to get my money back as bank don't seem to care about my loss, only getting their loss covered by taking my money from these purchases....

Are you sure you have not been scammed by the customer? If her card is not working, I never heard of the bank issuing you a code they send a new card

I found this online, [broken link removed]

yes she has scammed us, the staff know her well from been in and out of the business regularly and is (was) a nice lady, after investigations of her card number this has been going on for months, nearly a year now and my business has received the funds by her bank up until these 43 tansactions came to be known. they must have realised this earlier.... but to allow this to carry on with out infoming my bank is another thing that is driving me mad!!!! i am going to talk to gardai about this person, but what i really want to know do the banks have any responsibilty in all of this as i said before i have tried numerous cards as tests (knowing no money to meet amount been charged) all of these are declined with no option to force authorisation code....

Basically have i any chance of getting money from the bank or do i have to go down the legal route only

I would imagine because somehow you have "forced" the transaction through you will be liable. Your manual/contract will detail the chargebacks and what you are liable for.
I would contact the gardai straight away but would imagine by you using this code it was outside the terms ans conditions set down by the merchant service

Did none of your staff not think it a bit odd that the same person was coming in to do a cashback twice daily with an odd way of authorising the transaction? If none of them mentioned it are you sure that none of your staff are in on the scam?

Is there a possibility of you pursuing this matter through the Financial Ombudsman if you feel that the bank have been neglectful.