In some of your complaints I do think you have set the standards to high or I can't quite understand what you expect from AMEX.
Point #1 - If this was important to you why didn't you check on these benefits BEFORE applying for the card.
Point #2 - Don't know about Australia but in the US the concierges will also book reservations at other restaurants even if they are not part of the Fine Dining program. Just ask them to make the reservations for you if you don't want to call the restaurant.
Point #3 - AMEX cannot guarantee good service at the restaurant you dine at. I don't know of any credit card company that can. If anyone else does I would like to get their phone # so I can get that credit card. Did you complain at the restaurant? You personally complaining would have been better than calling AMEX and asking them to complain for you.
Point #4 - Should have called you back within 36 hrs. but maybe the restaurant didn't get back to them yet considering the date you want the reservation on.
Point #5 - Should have called you back if it was a simple reservation
Point #6 - You should receive some type of booklet outlining the details of the AMEX Plat. program. Included should be info on the benefits (Herz, Hotel Prog., etc.). As for the 2for1 Business benefit, it various from country to country and to which country you are travelling. To the best of my knowledge there is no written published details on the program in the US (just on the AMEX web site). When you are planning a trip, call the AMEX agent and say you want to book a 2for1 and they will give you the options available. If you are expecting a detailed list of which airlines serve which destinations as part of the AMEX 2for1 program you will never get it because it doesn't exist (to my knowledge).
IMHO you need to keep in mind that there are good and not so good concierges. When you talk to a good one, ask him/her their extension and try to work with them in the future. Overall I think the AMEX Plat. card is a great card but like all card it has its problems. You just cannot expect everything to be perfect all the time. One other thing to keep in mind is that the concierges (at least in the US) are employeed by a seperate company and not AMEX.