I had always been with O2 on pay and go right from the Genie sim card days up until earlier in the year when I left for Orange, anyway I have just returned to O2 today and find things have changed, I've had various pay and go numbers/sims over the years and its always been the same, 300 Free texts and a certain amount of free data if you top up £10 per month, anyway this sim doesn't appear to have anything free, I am being charged for texts 12p and data, having read the info that came with the sim I can get unlimited texts for £5, I don't want a bolt on as such I want them free. Unlimted texts are of no use to me as I only send about 20 a month max, I used to also be able to have say 100 texts and maybe 50 free mins. Have those days gone?

Nope, those days are still here - you just need to opt in; http://www.o2.co.uk/explore/tariffs/paygo

Exactly, there are a range of tariffs. You just need to choose which one you want.
You are currently on Simplicity, you'll want to change to Text and Web. Just follow the instructions in the booklet you get with the SIM or on the link above.