Viator.com complaint: Request for a refund

I paid for a tour of the Louvre Museum at which time I requested accessibility since my daughter is in a wheelchair. A few days before the tour I began to receive emails from the vendor stating that they were unable to take breaks or slow down the tour to accommodate my daughter. I asked f the facility was wheelchair accessible and they said yes. Closer to the date of the tour I receive our vouchers for the tour in which it stated that they could not accommodate wheelchairs. I requested a refund based on this information and was given $22 which I believe is their standard refund offer if any. As they weren’t able to provide the service that I paid for I initiated a chargeback complaint with my credit card company and they are withholding payment. I have begun to receive emails with a threatening undertone stating that I need to release the charge back or they will take other means to collect the money for something they did not provide.