Help with timing please,coming to the end of contract,with cashback,mobileshop.

Peakma

Hi I started a 12 month contract on O2 with the mobileshop on the 5th of may 2005.I got a great deal(hopefully) through R points(got £14 cashback off them) free phone,£25 a month for 100 mins and 100 texts ,and two vouchers for £150 casback each.I did the first one ,no problems,but I'm getting confused about doing the 2nd one,and ending the contract.(I don't want to fork out any cash,that I won't be getting back! as I hardly use it anyway)I was going to end the contract,but I didn't realise I had to send it in writting a month in advance!
(this is where I get confused???!)
So after speaking to O2 (who I found very pushy,not very intrested in answering my queries,far more intrested in me buying a new deal from them-are they on commision?)I decided that rather than cancel, and have to pay another £25 for another month,I'd switch it to pay as you go,and keep my number(which I think is free?).I asked them when I should do it ,considering my cashback contract.They told me I may aswell do it straight away,as I am noy using the minutes I'm paying for,and will still get the cashback anyway.But this didn't seem right? If I do this,will my contract not of been cancelled early and invalidate my cashback voucher? or is that all completely seperate.Will the contract still also be running,and cancel itself after the 12 months?I'm very confused and don't want to have to pay for timing it all wrong.
O2 sent me the stuff I need to do it,and when I originaly requested to do this they said it takes about 5 days to work.So when should I do it?
Thanks for reading this,I hope it makes sense,I've just taken 40 mins to write it!(slightly distracted by tele,but it's really hard to write down your confused thoughts! to try and make them make sense!)

jnm21

Well, bare minimum, don't change to P&G before 5th May, possibly wait until you have the bill required to cliam your £150 in hand before doing anything. You should be safe giving 1 months notice from 5th April, but I'd suggest that you consider trading off £25 for an extra month against risking £150?