Upgrade but keep Apple Watch

[Sadie0604]

I have an iPhone 7 Plus, with two years to go on the contract. I also have an Apple Watch series 5 with just under three years to go on the contract. I want to pay off my device plan balance for my phone, but I want to take out another o2 contract on Affordable Mobiles, as it is way cheaper than taking another contract out directly through o2.
If I took out a new contract with Affordable Mobiles, would I be able to link it with my Apple Watch? Seeing as the watch won’t work cellular, without an O2 phone...

[MI5]

@Sadie0604 

You must have an O2 refresh contract for the watch to work. Buying from a third party won't give you that.

To keep the watch working you need to upgrade directly with O2, otherwise you'll have to pay off the watch device plan too, so overall it will be cheaper to upgrade with O2.

[Sadie0604]

Thanks for your help. That is very irritating, as the price difference is unbelievable!