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Well the good news is that this doesn't affect people who are currently in contract with Vodafone. It'd be more concerning if this change was impacting people in term.
I suppose it'll be a case of people looking at their options when it comes to renewing but we'll probably find that if EE and Vodafone have made this move, I expect others to follow. It'll be a matter of timing.
So probably the best answer is watch this space...