Furious customer

Please tell me how is it possible for Vodacom to downgrade my 12 months contract but they refuse to give me a better upgrade when I've called them? I've called on Tuesday 26 March (15:46) to query the email I've received regarding the downgrade. When I've called for a better deal I saw on your VodaPay App, I was told I can't have it because I'm on a 12 month contract, but you guys can chop and change the way you feel like it. Then you might as well put me on a month to month basis and I can look for a better deal somewhere else.