Apple Watch SE error code 106

[Alps2]

On December 5, I purchased from an O2 shop, an Apple Watch SE and a monthly airtime contract for my IPhone 13 and the watch. 
Since then I have been unable to set up mobile service in spite of numerous calls to O2 support, and a response numerous times that a reset had been done, wait 24 hours and try again. Every time I get “Oops call 202, quote Ref 106”. No one seems to know what 106 means. 
I see many other posts about this but no solution. 
Can someone please advise me on how to resolve this problem. 
I transferred from Tesco Mobile to O2 for Apple Watch support but can’t think that would be relevant. 

[Cleoriff]

@Alps2 

I'll tag one of our account advisors @O2Sarah- who  will be on tomorrow from 8am

Hopefully she will be able to help.

[O2Sarah-]

Good morning 

Thanks for the tag @Cleoriff 

@Alps2 I will send you a private message so we can check your account. 

[Cleoriff]

Thanks @O2Sarah- x

[Robins]

Hi @O2Sarah- I also have this issue with error 106 when trying to add an Apple Watch to my account. Can you please help with this? 

[O2Sarah-]

Good morning and thanks for the tag. I will send you a private message so we can look into this for you.