over R 3000 for 3 gigs

I now have to pay over R3000 at the en of the month for 3 gigs of data because i upgraded my phone and put the contract and put the sim into my new phone without anyone telling me that my data on my old contract will just go on forever on \out of bundle rates"because i dont get data with it. And to make everything better they send me a kind message to tel me that the rate on my new contract wich i signed 2 months ago for a fixed amount is going to go up. How can they make me sign for a contract and then make the amount higher after i signed. That is very *****. Defenitely the last time i will EVER take out a contract with Vodacom."""