Welcome to the Community and thank you for getting in touch.
I am very sorry to hear this has happened to your friend.
When a new SIM is ordered we do have the option to send it for self activation or already activated meaning the current SIM disconnects. From what you have advised it sound like the SIM has been ordered pre activated which isnt something we would usually do but without being on the call we would be unable to confirm was was discussed.
Has your friend received their SIM as we would usually advised 3-5 working days for delivery via Royal Mail.