Getting out of a contract through the T&C's?

I received a letter this morning from 3 telling me they're changing their call pricing structure so that any call lasting less than a minute will now be rounded up to a minute.

I'm not fussed about this in the slightest but have just got an iPhone, so the 3 contract is of no use to me any more. Can I get out of my contract due to them changing the terms, albeit ever so slightly?

This is from their T&C's

4. Variations to your agreement or prices

Pay Monthly Customers

4.1 We may vary any of the terms of your agreement, including our Price Plans, on the following basis:

1. any updated Price Plans and new terms will be available on our website and on request to 3 Customer Services;
2. if you are a Pay Monthly Customer, we will let you know at least one month in advance if we decide to:
1. discontinue your Price Plan; or
2. make any variations to your agreement which are likely to be of detriment to you; or
3. increase the fixed periodic charges for your Price Plan (if applicable) by an amount which is more than the percentage increase in the Retail Prices Index Figure (or any future equivalent) in any twelve month period.

You can end the agreement for such variations as explained in Section 10. Subject to the above, you will not be able to end the agreement if such variation or increase:

1. is due to changes to the law, government regulation or licence which affect us; or
2. relates solely to Additional Services; or
3. relates solely to Add-on(s) (if applicable to you).


10. Ending this agreement and Disconnection of 3 Services

Pay Monthly Customers

10.1 You may end this agreement in the following ways:

1. In certain circumstances under our Returns Policy. You may need to get in touch with 3 Customer Services to arrange Disconnection.
2. You can end the agreement during your Minimum Term (if you have one – this will be stated in your Price Plan) by giving notice to 3 Customer Services at least 30 days before the date you want to end the agreement. However, you must pay us all the Charges you owe, plus any Cancellation Fee for your Price Plan (as set out in the Price Guide).
3. On 30 days' notice, outside the Minimum Term. You can end the agreement if your Price Plan does not contain a Minimum Term, or if you want to end the agreement at the end of your Minimum Term or any time after your Minimum Term has expired, provided you give notice to 3 Customer Services at least 30 days before the date you want to end the agreement. (A Cancellation Fee will not be charged.)
4. Within one month of a detrimental variation to your agreement. You can end the agreement within one month of us telling you about a variation to your agreement (which includes your Price Plan) which is likely to be of detriment to you. You must give written notice to 3 Customer Services within that month and your agreement will finish at the end of that month once we receive your notice. (A Cancellation Fee will not be charged.)