Unprofessional service from Planet fitness the Marc

I joined planet fitness the Marc, in 2019 early or mid year. A month after joining I found out I was pregnant. Write an email to them to cancel the contract and this is when the drama started. They told me that cancellation fee is a rediculous amount of about 6/7k rands. I emailed them back saying I wasn’t aware and why such a ridiculous amount. Fast forward after the back and forth, they have sent lawyers claiming I have to settle a bill of 18k I am owing. In all of this I have nothing from them, not even a tag. @planetfitness