Need help with credit card, poor feedback

I attempted to purchase something with my credit card on the weekend (Friday 15/05/2015) online with my credit card, to no avail. I kept getting an error message and upon trying the same credit card on another website it did not work. I have previously bought items online on my credit card and I cannot understand why it does not work now. I then proceeded to email absa on Saturday about this problem and obviously they can't respond on the weekends, so I tried to phone them and was on hold for 40 mins upon which I gave up. I eventually received an email back (on Monday) saying I can't purchase online with a debit card, after I EXPRESSLY stated it is my credit card account, and even sent them the card number (my credit card is linked to my debit account which they could obviously see on there side). I then received a reply that my complaint will be sent to the credit card department yesterday, I am still waiting for a reply and I'm fed-up because this should have been sorted on Saturday already. Poor poor performance absa. This is seriously making me reconsider moving to a bank with better support when my studies are over, this is unacceptable.