Thanks for your post and welcome to our community.
Sorry that the new SIM has caused you some concern, I know you'll be keen to get some answers.
We're sending new SIM cards to all customers, we've been doing this for a while and now we're hoping to get the last few customers changed over to ensure you're getting the best from our services.
The new SIM card doesn't mean a new number, everything will stay the same and it should work with most phones, however some very old ones might not be compatible. If the handset gets locked or needs an unlocked code then we'll be able to look at getting an unlocking code for you.
The SIM will come with some instructions on how to activate it but if you're having trouble then we can help from here.
You shouldn't need to do anything else put do pop back if you have more questions 🙂