10+ year user of TT.
Got similar problem, if not worse:
I discovered PaW discount BEFORE I paid for TurboTax (but has mostly completed input my tax info). Went thru the login from the PaW site and was still not credited with the $20 discount.
Poor show not to offer a PaW code that can be input before payment when troubles like this exist. Or you should refund the discount to the customer and not issue LUDICROUS statements like "it can't be done" in the 21st century!!!