R500 Cashback Joining Promotion - ****

I've joined Virgin Active in January this year when there was a R500 cash back promotion. This appeared to have been a **** since I never received the cash back. They say first debit order didn't go through so that was the reason for not receiving the cashback. My banking details were captured incorrectly, they put a blame on me even though it's the staff from the club who made a mistake. My banking details were later corrected via the phone and my account was debited immediately. I'm very disappointed in how they handled this matter considering that mistakes were fixed and that all payments were made. This appears to me as a trick or **** in order to attract more people to join the clubs.