New data plan not working with upgrade

[Kimmyyy]

Upgraded my phone and my old number is working fine on my new replacement sim. 
However my new data plan hasn't kicked in. When I go into My Sims on the app it tells me I still need to activate my new sim it but then the page goes blank when I click on it. 
How do I get my new data plan?! 🥴 Please help

[PandJ2020]

If your number is unchanged then you either physically moved your SIM from your old phone to new or you've activated your new SIM as a replacement to the old.  (Which simply deactivates the old SIM and activates the new as a complete replacement)

Any new data plan would only activate on a new SIM with a new phone number.

[caesarome]

The new data plan will be on the new sim only so if you activate that you will be paying for this second sim with a new number so if you are happy with this then using the phone that has you other sim in it call Sky on 150 to get it activated.