Cell C unable to resolve issue!

I've had my number with cell c for more than ten years. I migrated to vodacom earlier this year due to cell c's poor network in the area I relocated to. When I discovered that cell c resolved their network issues I then migrated back to them. The new sim that I purchased was a data/home connecta which I learnt after porting that it doesn't meet my requirements as I need minutes and not data. I purchased a new sim card, contacted cell c and requested to change my package but to keep my cell number. They advised that it is not possible and the data sim/home connecta number is for life, which I find quite ridiculous. Ater some to's and fro's the call center agents suggested I change my number but they obviously don't understand the impact. I still find it unacceptable that cell c cannot assist with my request.