cannot use credit card

I have a woolworths credit card, which I could use then all of a sudden they blocked it as my previous credit card which I had like 3 years ago is still reflecting. I called in numerous times, no one calls me back and they promise to call me. I have spoken to about 20 different agents. not one person can assist me at the head office not even team leaders or supervisors. now I have a credit card I cannot use but my monthly debit order payment is prompt.