Surely the issue of contract price increases whilst still enforcing exit penalties is covered under the Unfair Terms in Consumer Contracts (UTCC) legislation:
http://www.oft.gov.uk/about-the-oft/legal-powers/legal/unfair-terms/
http://www.legislation.gov.uk/uksi/1999/2083/contents/made
Essentially this legisltation prevents contracts from being enforced which are completely biased in favor of the vendor, and against the rights of the consumer.
In the case of mobile phone price rises I have succesfully used UTCC to leave contracts without penalty, because whilst the contract does contain a clause allowing prices to be raised - when used in conjunction with a contract exit penalty the net effect is to bias the contract completely in favor of the vendor. I.e. they could effectively raise prices as often as they like, and by however much they like and still charge an exit penalty.
UTCC applies at this point, by only allowing the fair terms to still be enforced, and preventing unfair terms from being enforced. In my case, I offered the telecoms company the choice of keeping the contract price the same, OR allowing me to leave without penalty. But they cannot legally apply both contract terms as that would be unfair to the consumer under UTCC. They chose to allow me to exit without penalty - so I suggest anyone having similar problems studies up on the UTCC regulations.
Biting the hand that feeds IT
