Hi @Abi16, Upgrading would mean entering into a new 24-month contract, and if you don't want to remain on Bill Pay for another 24-month period, I would not recommend upgrading. As your phone is in good condition, I understand you considering your options. Have you had a look at Sim Only? No longer term contract and you don't have to remember to top up.
If you want to talk through your options, I'd recommend clicking here and chatting with our messaging team, they'll let you know all your options and share any available promotions.