Vericred - No service but keep charging me interest!

I have been receiving sms,s from this company for months about an apparent outstanding amount on my name. I have tried calling, emailing to get the information and no one ever responds. And they still keep charging interest!!! How can I pay something if I do not know what it is for and if they cannot provide any info.

Still no pmnt on your MEDICAL acc. Pay today: ABSA VERICRED GENERAL TRUST