You could flat out deny anything that is a business transaction dispute but I don't think that's the best approach.
What type of agreements do you provide to the business customers? If we are giving debit cards to our business clients, we tell them that they are solely responsible for the transactions and security of the cards. In situations where a fraudulent transaction has occurred, we will do our best to investigate and find a resolution. But, they're still liable if no resolution can be found.
VISA rules still say that you must give provisional credit within five days (as opposed to Reg E's 10) and I don't know if they differentiate between business or consumer cards. I doubt it.
If you need a copy of our business debit card agreement, PM me and I'll send it out.
My opinions are definately my own. I could be wrong. But I don't think so.