Hi Barney,
Welcome to AGL Community.
I understand that situation would be concerning, especially with all the scams around these days. I am glad that you have now received a copy of your bill.
When we have issues with issuing bills the first time we automatically issue the letter to keep you in the loop of what is happening with your account, in your situation it sounds like the second attempt to send the invoice was successful leading to this confusion.
Of course if at anytime you are concerned that there may be an AGL related scam that you are being targeted with feel free to let us know here so we can get on top of that asap.
Thanks for reaching out.
Ellen