T-Mobile (part of Everything Everywhere) are to increase monthly contract prices in the UK by 3.7% from the 9th May 2012. This affects all contract customers that took out or upgraded prior to 1st February 2012 as any contracts after that date already take account of the price rise.
The terms and conditions on T-Mobile contracts state that they can increase the contract prices in line with the Retail Price Increase (RPI) in a 12 month period. The RPI as measured in February was 3.7% and so they are increasing it by the maximum available to them.
This comes only months after Orange, the other half of Everything Everywhere, put their prices up by 4.34%.
More details about this price rise as well as a calculator to help you calculate how much more you will pay can be found at http://support.t-mobile.co.uk/help-and-support/index?page=home&cat=NEW_PRICES.