secondary SIM card

[Lin001]

I have renewed my contract with 3 and I purchased a new mobile phone. I transferred the SIM card from my old mobile to my new mobile phone, as instructed by the staff in the 3 shop in Carmarthen. I was given a secondary SIM card and I inserted that in my old mobile but the secondary SIM card has a different mobile number. I have removed the secondary SIM card from my old mobile phone because I'm worried that I will be charged for using the secondary SIM card which has a different number. I have tried to telephone 3 but everything is automated and I cant get to talk to a human being. Why doesn't the secondary SIM card have the same number? Can I order a replacement SIM card which would have my correct number? Any advice or explanation would be gratefully received. Thank you.

[PeteG]

Hello, Lin. 

It sounds like 1 of 2 things has happened.
1st. The upgrade that you completed might have came with a PAYG SIM card, these are often provided with upgrades as a spare, or something you can put in your old phone. PAYG SIM cards will usually receive a couple of texts at the start when you first insert them, informing you of the phone number for the SIM. You might also get a text about topping up. Another way of identifying the SIM is to check the packaging it came in, as it would say 'PAYG', or 'Pay as You Go' on it. 
2nd. The upgrade wasn't an upgrade, and you took a brand new contract instead. You would have the old active contract, and the new one running at the same time. If this is what's happened, you wouldn't have the same texts delivered to the phone after inserting the SIM. 

Does any of that information help you identify which of the two scenarios you are in? 

Pete.