what's our exposure if we do not pay for a chargeback?

We have a vacation property listed on VRBO. Yapstone handles their credit card transactions. Recently, a tenant stayed for 1 week of a 2 week reservation. After 1 week, they wished to leave early so we offered to refund their money for 2nd week. They agreed to this in an email. We refunded the amount promised. They then had their credit card company issue a chargeback for the entire amount. We disputed chargeback & also closed our bank account connected to VRBO. Yapstone was therefore not able to withdraw the chargebacks from our account. If we do not reconnect them to a new bank account, they say they'll suspend our account. We're fine with that. We're not happy with VRBO & don't intend to rent our house out any more. Especially when all a tenant needs to do, after staying in our house is to claim that "the accommodations were unsuitable" and they'll almost certainly get a full refund. What's our exposure if we do not allow Yapstone access to our bank account?