Been sent wrong ee sim

[MSingleton]

Ive been sent an additional sim as I'm on eeone essential sim. So got extra 1 for my friend. But the sim sent out is the wrong sim so I rang ee to cancel the ee sim. So they sent me in post the correct sim. But have taken the right sim off the app.

[bristolian]

How do you know one SIM was wrong? And by the same token, what made the other sim, right?

Were these additional pay-monthly lines?