Entering my A3 number always worked. Sometimes (alright, MOST times) I had to tell them A3, to do so, but then it mostly worked. Only a few (apparently rather "smart") agents couldn't do so, then I simply did retrocredit, which always worked.

Lounge access, on the other hand, is much more difficult. I hit A3 *G early this month, had couple flights, with the lounge ladies in ZRH letting me in twice, and the dragons in FRA+MUC with their typical german friendliness (or better said, the contrary off) simply telling me to get lost.. had to grab my FTL card to at least be able to access the C lounges there, as apparently in Germany it's "No Real card, no access" - no matter if you've a statement which clearly shows that you should have access. At least I'm hitting SEN now too, hopefully that card arrives quicker..