Gold's Gym Membership Collection

I had a Gold's Gym contract in 2013 in West Valley City Utah. I moved to Albuquerque New Mexico in August 2013. I can barely remember all the details but I distinctly remember informing them of my move and canceling my contract. I always paid my dues on time and I honestly cannot remember if they told me I had a balance because it's been so long. I moved over 500 miles away and there are no Gold's Gyms in the state of New Mexico. I told them of my move and turned in my key ring card. I've since lost all correspondence. Today I receive a bill from a collection's agency for $605.04. $401.13 principal; $203.91 interest; service date 09/26/13. I do not owe this money. What is the best way to dispute?