Airport lounge charges

I was billed R430 per airport lounge visit and have been charged R1290. Diners club has recently changed the rule where a minimum spend of R5000 is need to qualify per free lounge entry- i found this information out after calling the call centre where the lady could not prove to me which entries were 'free' and what was for my account. There was no communication to me for these fees, if that was the case i would have used my other cards to enter the lounge for free or foregone my entry. Now i'm sitting with this high fees and am certain that i will be receiving more charges. I can't believe i was charged these fees and would like for Diners to reverse these fees as i was not informed. I believe it is unfair to charge your customers due minimum spend, free lounge entry was always free in the past. Why would you include charges now! This is terrible!