Unfair treatment by Zone fitness gym

Hi, i had a contract with zone fitness gym for few years. my contract with them expired after few years. We did not renew the contract but i did enquire if i needed to renew my contract i was told that going forward it becomes a pay as you go. however we were informed that the gym is moving... so i submitted the cancellation letter because i couldn't attend the gym anymore hence they were moving away from my work place. to my surprise i received calls informing me that i owe them and they are handing my account to the lawyers. please assist.