After 10 years wanting money for an ended contract

Just received an sms from a lawyer saying Planet Fitness wants to collect R4256.69 from me for an contract I ended and I quote ended years ago!!!!! I was 21, the contract is paid up and now after 10 years they pull this nonsense!!!! Planet Fitness is not even a gym in Port Elizabeth anymore!!!! What the hell man!!!! This is pathetic, after 10 years!!!! Pathetic gym, trying to make money from people who ended a contract with them