Swap Apple Watch mobile data plan to different phone

[BigBri165]

I have a couple of Apple Watch series 5 synced to phones on the same account - but I want to swap the phones over but keep the watches attached to the same number.
I have paired the watch and tried to set up Mobile Data on the Watch app but get the error “please try again. If it fails call 202 and quote refenernce 04”
I can’t seem to find anything regarding reference 04 so I’m assuming it’s because the watch data plans are synced with different phones...? If so can I swap the watch plans over?
Many thanks and stay safe!

[Cleoriff]

I think you will need to contact O2 @BigBri165 

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