CHANGE CONTRACT NUMBER!!!!!!! IS IT TOO MUCH TO ASK?

I unfortunately signed up for a contract with Vodacom at the end of January. I was allocated a new number even though I indicated that I would like to use my current number, which is prepaid vodacom number and I have been using it for 17 years. I went to the Vodacom store and requested a change of the contract number as everything I use is linked to that number, personal and business. I was told that it's not possible and I must change SIM cards whenever I want to use contract data/minutes. Meaning for the duration of this contract I will be paying to be inconvenienced? How can that be Vodacom? Both numbers are with Vodacom. I went through Twitter and other platforms and noticed that other people have been having this type of issue but as a company you have not seen it fit to find a solution to this and make it easy for your customers to change? I wanted to change a vodacom number for a vodacom number :-( At this point I am willing to cancel this contract and go to another service provider.