No commitment as signed.

I joined the aerobics class as I have been a member before. But a new instructor was now also giving classes. I didn't complete the contract yet and by the second evening class the instructor told me that because I'm the only attendee she won't giving class. Therefore they expect me to pay them for a service I didn't receive. The owner knew about what happened but didn't contact me to apologise for what happened only to ask when I'll be making a payment. I then said that I won't be making payments and now their lawyer keeps calling.