Stop Harassing me

I made an arrangement To pay the installment I missed due to problems I had a work and It was agreed that I'll pay it over a span of 4 months. Mr Andrian Du Toit called me to confirm that. Now I'm getting harassed by the collections department. They call everyday and when I pick they drop the call, I check the number and it's netbank mfc. I'm honoring the part of the deal so I don't know why am I being harassed like this now with calls and sms. I'm very disappointed with MFC, when I moved from absa I thought I was going to a better bank, I was paying more in absa but at least the service was professional.