Bad service and reaping people off

I joined the gym in 2015 at zone fitness bruma I only managed to attend1 month and the following month I had lost my job. I then requested to cancel as I dnt have the means to pay for it. I spoke to Hilda and was told to bring a letter to show m unemployed and that it will be canceled. Now I have been handed over with a ridiculous amount that is damaging my credit history. On the 27th of September 2019 I called and spoke to anikie who said there is nothing to be done on their side, which I believe it's a lie