Cant use my phone at all after going onto prepaid

I ended my contract with Vodacom on 31 10 2015 and migrated the sim to a prepaid number. However since they have done this I am unable to use my phone. I called Vodacom to explain the situation and they cant give me an answer as to what the problem is. I eventually got the phone to receive calls again but i am unable to receive or send text message. Vodacom your service Sucks. I will not ever promote you for any family members or friends. <br>