Just phoned up o2 CPW to change my tariff to add more minutes, After checking if it would affect my redemption deal the guy came back and said i could have 200 extra minutes and 250 sms for no additional cost . My deal is £40 a month with 3 cashbacks of £100 each time making the cost of my rental £15 mth . I was on 400 mins and 250 sms previously . My contract is 7 months old now so ive only been upgraded to the latest tariffs that new customers would get , but if you are on a old plan like i was you may be able to get your tariff updated with more minutes and text to the new ones at no additional cost also .