Switching from British gas to npower

Valley's_girl

Hi just after some advice I have prepayment meters with british gas, for gas and electric, tomorrow I am switching to npower.
I am a bit confused about the changeover. I haven't received any new card, or key for the meters, npower want my meter reading tomorrow.

This is where I am confused I rang npower today to confirm about the switchover tomorrow, I enquired and asked about not receiving the new card and key the man said I won't receive a new key for the electric I will have to take it to an outlet for the key to have a new code installed on it.
He said he would transfer me to another man who had more info on it, he came back on the phone and I said I must ring tomorrow and the man will explain how it works.

Just wondering has anyone changed over and is this right. I am a bit worried have I done the right thing. I wasn't told this originally by the man that called to my house he said I would have new cards.

I hope that this makes sense.
Thanks in advance
Best wishes
Ally x