Hi, we never received any "physical" letter, each one of us received an email, I got mine 1ST and my wife's arrived 2 days later.
Also, I was reading your other posts, and yes you have the IMM 5401 receipt, it's the PDF you printed out after paying the fee online.
In your case you should definitely call them, I know it's a pain, but you gotta do it, they are famous for losing processes, call 3 or 4 times if needed, get 3 or 4 different answers as usual, but make sure your process is there, if it isn't you'll have to grab your post office receipts and go to fight... Don't let this linger.
Good luck, and above it all remember, patience is the name of this game, remember it might be going hard now, but it shall pass sooner or later, I have been here, 3 1/2 years now, almost lost my mind at a certain point, so I had to come in terms with it, it is what it is, problems come, problems go, grab it by the horns and keep on fighting