I pay £20 pm for 500mb data, unlimited texts and 100 mins. I only use about 15 mins, all of the data and about 100 texts. It would be cheaper to use PAYG wouldn't you think? Am I ripping myself off... oh well only 23 months to go before the contract expires...

You would be much better off on Pay and Go. A £10 top up on O2 Pay and Go would give you 500megabytes, 300 texts and the £10 to spend on calls (with 10% back every 3 months).
Of course you'd have to buy your own handset.

I think the OP may have just taken out a contract so might have to keep it.

For me I got my N900 on T Mobile at £15 for 1GB data 300 mins and 300 text which was about 3 months ago and am quite happy with this.

Before I had N97 on Three which was the same but at £20