Unhappy client - do you even care?

I have 3 contracts with Vadacom (part of the ANC now?). I want to buy data on my one contract and transfer it to another sim and device. They won't allow me to do so. State T&C's are the issue. BUT if I buy data, put that sim card into a device and use it, it will be fine. How is that for reasoning? I do not want to swap the sim cards all the time. It is exactly the same thing, I just want to use 1 device! Terrible service. Contract closed and so will the nest one also be cancelled....and the next one.