Can you just decreases my limit!!

I didn't think a simple task such as lowering my credit would be so difficult, how much more difficult will it be to close my account am I indebted to this account forever. I have another account with another retailer one call my credit was decreased immediately. But it's been mission impossible to decrease my credit on my Jet account. I Called in October it was said it would be done, I followed up late November I got an sms saying it's done. But come December I received my statement and surprise suprise my credit limit is not decreased. I received an email today that it couldn't be done, no contact number nothing. My goodness can I just get assistance!!