Upset and Disappointed customer

i have a contract phone with Cell C and the contract expired after 24 Months which was last month i was asked if i wanted an Upgrade and i said i did not want an upgrade but wanted to continue using my phone number as prepaid and no longer contract , to my surprise when i couldn't make or receive calls i called the Call centre and was told my number was closed permanently and asked if it could please be re-opened but was told that was not possible,what makes me upset is that i was never told that its going to be closed i have had this number for two year everyone knows this number and all of a sudden its closed and cannot be re-opened. if this is the kind of service I'm receiving from Cell C i don't see myself using their services again and would not even recommend it to my friends and family.