they over charge clients

I paid 1yr advance membership fee. Now they barred the entry on the gym. They terminated me using their service. They want me to pay R399. I was not aware of. Since they terminated my service. I need the refund for last 6months advance I have not used. Hence they prohibited me from the gym. I need the refund. If no respond will take it to facebook and twitter. People becarefull of planet fitness special of R199. Never sign that contract before you read it word by word