account for free membership

my son signed up about a year ago for a month free membership, he did not receive a membership card to use the facilities, at that point in time the amount was about R400 , now we are constantly getting call from virgin active to pay over R1000 . i am not going to pay for facilities that were not used and still ripping us off, i have taken this matter up with virgin active with very little response , this is ****************.