HazelMcW - or could you stick with the current phone, get a SIM Only deal, and pay a very low amount for your needs...
At the moment, the Panther SIM Only 12 month deal is £10.50/month (reduced from £15.50) giving 300min, 500 MB internet, 'unlimited' texts. If you go via Quidco, you'd get £80 cashback, which means your cost would be around £50 for the whole year - ie under £5/month (but Quidco charges £5/year so that would reduce any savings a little).
Orange SIM only deals
Of course, to do this you'd need to get your PAC from Orange, move the number to another network, and then go back onto Orange (and then, as a "new" customer, the payout via Quidco should reach you within a number of weeks).
Unfortunately, the £80 cashback offer ends on Sunday, so this option isn't really possible but gives a flavour of what might be possible if you could cope with using a PAYG mobile for a short time to be able to move your Orange number away, and then rejoin Orange with a better deal.
If you do get a PAC, you might have Orange ringing you with offers at which point you could take some deal, but you'd probably be spending more than under £50. It might get you a newer phone, but would you really be spending any less than you are at present?
You can see it could be best to be prepared at some point in future, to move your number away even if it was just for a week... and then move back, if the Cashback deals (from Quidco or TopCashBack) make it worth the minor hassle.