Nuisance Calls

I have a debt with MBD which I committed to paying a few months ago. After each payment instead of the debt decreasing it was going up. then I decided to stop and focus on debt that are showing progress. My issue with them they are forever harassing me with calls, even if I decide to pay them. They will call and force me into making a payment arrangement. I wish they could stop calling me because they are irritating me.