Mtn. Always going back on their word

I had made a payment arrangement with mtn as i lost my job and missed payments. The arrangement was to pay 900 per month. I have eftd the money 2 weeks ago and now i have been cut off. They then state that i must pay 75 percent up front... Why even make a payment arrangement then?? So i guess i should just breach my contract too and not pay and shift to prepaid. Seems its the ayoba way. Lets ignore the customer shall we? So i will not pay another cent to mtn until someone actually picks up the phone and explains how they can change payment arrangements as they see fit. Dunno why i even upgraded. In my opinion? Stay away from them