1) They DID start a MVNO, called LIFE, that was probably part of the problem. They were competing with their own suppliers.
2) Neither Voda nor EE renaged on their deals, they just anounced that they wouldn't be renewing them. They did this because P4U wouldn't or most likely couldn't offer them the terms they wanted. P4U was saddled with a shed load of debt, so likely couldn't afford to do this. The shops that Voda and EE were interested in were ones that didn't clash with their own store networks, and are thus unlikely to be the most valuable.
Biting the hand that feeds IT
