Virgin Active Unfairly Listing me

about three years ago I joined virgin active but however I was unable to use any of their facilities due to some reasons. Now they are demanding that I pay them an amount of about 4k because I signed a contract with them. My issue is that since I never ever used their services we should come to some sort of reasonable amount as I feel like paying the whole amount is a ******* and I wont be able to afford it. They have handed me over to MBD for collection and I am harassed and threatened by them everyday. Please assist as this is my hard earned money and I just cannot accept or afford paying the full amount considering that I never even for one day used their facilities. Now they have listed me on ITC as a bad payer just because of a silly gym contract. My name is Mandisi Nyathi & my cell number is ********** 308.