Credit cards limits

I have been an absa customer since 2002. For many years I have been very satisfied with the service I received, up and till now. I am a bit puzzled, all banking institutions draw up and analyze affordability for credit cards, then they give you a credit card limit and that is what you can spend. Well with ABSA I was approved for a credit limit of R20 000. I was shocked and surprised when I had a debit order of R65 000 on my credit card. I did not sign any documents that say I have an overdraft facility. Now my question is: if I can only qualify for a R20 000 credit card limit, how does ABSA allow a debit order of R65 000?