Amended payement method without my consent

I have been a loyal customer of MTN for some time now and regret to advise that your services over the last 8 months or so, has deteriorated to such an extent that I no longer feel like a valued customer. My recent experience has really left me with no other option but to relook at the services/non service that I am enjoying. My account has been unfortunately moved over from Nashua Mobile to MTN direct. With Nashua Mobile I always got fast, efficient and excellent service. I wish I could say the same about MTN.<br> With Nashua Mobile: <br> I had a reminder that would let me know when I approached 80% of my call limit. If my phone was to be soft locked I was able to go in store and increase my limit for that particular month without any hassles. Being serviced by them was definitely a pleasure.<br> With MTN:<br> I get a reminder stating that my service has been suspended. What is the benefit of this? I cannot increase my limit for that particular month if my service has been suspended. I have always been on a debt order facility, but to my surprise I have been advised that as of this year my payment details have been amended to cash without my consent. Who authorised this as I am now suspended?