Disputing a debt

At first I was only disputing a portion of the debt, now I am disputing the entire amount (and am wondering if I can request a refund). About 1 1/2 years ago I was at a health fair through my work. While there I signed up with a membership at Gold's gym. While I was doing this I explained that I have spina bifida and due to this need to excercise in a pool. I was told that currently they did not have a pool but a gym would be opening up in 2 months that would. In order to secure the current price I signed up then with the understanding that if, at any time, my doctor felt I was huring myself I could terminate the contract with his recommendation provided to them. So January came around and I called and the gym was not opened and then about a week later I fell and did some serious damage to my right knee so I focused on that. At the end of February/beginning of March I called on the gym again and it still was not open (as of today I can find no evidence that a gym like what I was told even exists - it's not in the paper or their website). I emailed the company and complained. I never got a response. In April my automatic debit bounced. I got a letter and responded to it and also requested a form to terminate my membership there for health reasons. I got no response, instead I got a collection notice for the full amount of the contract. I mailed them again telling them pretty much everything that I have told you and got no response. I don't know where to go from here. I just sent validation letters to 2 other collection agencies but due to a recent move (that occured the day after I was placed on 3 weeks of bed rest) I can't find anything with the collections agencies address for the gym. Does anyone have any suggestions on what I do from here? I want to write them another letter certified but don't know if that will do any good. I don't think that I owe them anything since they did not fufill their end of the bargin and lied to me. Any suggestions, and FYI I was writing a post about this and it disappeared so sorry if 2 pop up. Thanks.