Charges for a free service!

Diners club offers you a card on the basis of benefits to use the airport lounge for free. you make use of this facility and then you find a bill of R180. when you query this a consumer nobody gets back to you. I took this up with their credit office and because my card is paid up I'm now told that i need to spend 12 000 every quarter to qualify for the free facility. I then raise the concern that this was mentioned in the sales call. I was promised to sent a recordings and 3 months later they haven't sent a call or responded to my mails. they continue to charge interest and now I apparently owe them R500 for using the airport lounge!