Worst service ever

I joined the gym when I was Fit and willing to gym , my contract was for 2 years , however during my contract I had a knee injury and was unable to gym , having advised them of my situation the answer they gave me I made an arrangement and have to stick to it , how can I go to gym when my knee is giving me problems , I did not predict I was going to have any injury .. I was so frustrated that no one had cared n I’m being charged for not going to the gym when I’m unfit to do so . It’s ridiculously stupid . It’s pathetic how they go so far just to get a sale ... Done With Them