I signed up for an 02 contract last April, it's for 18 months, which ends this November.. When i first signed up i was on 02 online15, which was £15 a month.. But soon change to 02 (30) and then eventually (40)

As far as i'm aware 02 charge the line rental for your remaning months, so will i be charged the orignal contract of £15 or will i be charged £40?

im guessing they would charge you, your original monthly rate, but i would ring them and ask tbh, if they say £15, then you could just tell them there and then you would like to end it.

Better still don't phone up just yet to cancel it. First phone them up to change it back down to a £15 tariff. Leave it a week or so then phone up to cancel and you'll only get charged £15 per month cancellation charge.

when I was with O2 the rules were as follows:

you CAN move down to a lower contract..... but only down to the next lowest one...... and you can only change it once per month.

Also - there's no VAT to pay on remaining months once you've cancelled, so this will be deducted when you make the final payment.