Varsity Tutors review: Charging for hours that I not aware of and not keeping promise when trying to credit me these non used hours

I made a deal with them for 4 classes for my daughter back in April 26th. When we were done with the hours, and just to be safe, I sent them a message confirming that I do not want to renew any other deal. In September I needed other classes for my other daughter, so I called them to discuss buying more hours. At my big surprise, I found out that they were charging me since April. I was so frustrated and mad on the phone that the agent offered me a solution. She stated they will credit me 16 hours and I have 6 months to use them without any condition. I scheduled classes with the teacher and after 4 hours they locked my account.
These 4 hours was challenging to use, with all the technical issues, problems on the app, to choose, keep the hours. Sometimes they will cancel the class the last minute.
I called to figure out what's going on and at my surprise, they didn't know what I was talking about. They don't keep records of their customers` calls. What a waste of time, energy, getting frustrated and having to repeat the whole story from the beginning. I had to ask them to do investigation and listen to all the recording of my conversations with their agent. After that, they called me offering nothing but diplomatic, passive aggressive answers that means that I do not owe them anything and that my money is gone.
Such a frustrating experience, we lost money, time, energy and trust...How can you work with vulnerable parents or students and charging them without offering them the service?