Can’t activate replacement SIM

[RachelHaynes]

Hi, 

ordered a new phone (16e) and tried to activate the replacement SIM (new data plan but not new number, already a Sky Mobile customer) but it hasn't worked. The SIM is in the phone but still has the old data plan and it won't allow me to activate the new plan. Every time I enter the activation code it says there's an error. I'm not sure what I can do? 

[GD1]

@RachelHaynes  You shouldn't need a replacement sim if you upgraded a data plan.n  You just use the current one.

[PandJ2020]

You cannot (easily) order a new data plan AND keep the number.  Any new data plan will have a new phone number.

You cannot transfer a number between SIMs via PAC code.  If you activate a new SIM then you'll have 2.

If you activate a replacement it will have the original dataplan.