RPI+/CPI Price Increase - Each year, your Pay Monthly airtime tariff will be adjusted according to a Fixed Annual Price Change (Three), RPI+ Consumer Price Index (EE, Vodafone) rate of inflation. Your bill will be adjusted in March (EE) or April (Three, Vodafone) by 4.5% (Three), or the rate announced in January (EE, Vodafone) and February that year (plus 3.9% on EE, Vodafone).