GiffaGaff For The People By The People. (I love this idea)
So my idea goes like this- Instead of having set plans i.e £12 for so many minutes, texts, and data; you have the option to pick how many minutes, texts, and data you want. The cost is processed from the relavant ammounts you choice, and everyone is happy (hopefully).
I'm not sure if this makes much sense (the festive times have certainly catched up with my senses) so I've attached a picture I created on paint. You're welcome to even use my wonderful 'slider' idea and the catch phrase.