Taxify charged me twice

Well the service had one particular thing that was concerning. I was charged twice. Apparently the "system" was not working and the taxi driver told me that we needed to pay cash, so we did. We also got charged on my debit card. So I called the driver and she said that she only selected to charge cash and that she never selected to charge on the card. So what do I do? She was very nice and seemed trustworthy, but I feel I was kind of ****med. This is my first time using taxify, I've never had this situation with Uber.