Loop hole in the system - Customers due for an upgrade will end up signing up with another service provider

I am rather frustrated at how silly it is to not be able to upgrade a contract on a new sim card without having to port numbers..etc. I have to wait to cancel my current contract completely, use my existing number as a pay as you go and then take out another contract and the consultant tells me that I won't be able to qualify for the daily specials. To be honest by the time this happens, Telkom would have a deal which is better and I will end up taking the contract with them. And Vodacom loses out on a 24 month contract. There is definitely a loop hole in the system. My identity no. should be the deciding factor!!!