No. Lost

I did I sim swop 2days ago and this morning I put in the new Sim card it has network but when I call I get a "Sim not registered error" I called vodacom customer service only to be told the worse useless answer, I was told I can have the no. Back because it has been deleted, njani I don't understand my last recharge is under a year ago how do they select which no. To be deleted worse I heard is inorder for me to get the no. Back I must apply for a contract I don't know whether that's their new marketing strategy or what but I am not happy I need my no. Back it's the no. I have been using for the past 10yrs I can't just loose it like that I am sure there is something that can be done for me to reclaim my no. Pathetic service received from the call agent