Sir,
I work for the largest Airbus operator in the world. It's an interesting but not really important little fact. This carrier is an combination of many carriers and all of them had a strong history with Boeing or McDonald Douglas in prior years.
I have been involved with training on these various aircraft. The Airbus is like the Borg. You will be absorbed. It is not like anything else and things you do routinely in other airplanes you don't do in an a Bus. I don't know how to describe it except in some cases the more experience you have the harder it is.
For one thing the FMC logic is very different in the Bus from the Boeing. Auto-thrust is an often contributing factor in problems. It is not as visible as in the Boeing due to no visible thrust lever movement.
Most problems I have seen deal with FMC / Auto Thrust / Flight Director mode awareness. The airplane can slip quietly from one to another level and if you are not right on top of it you don't see it. There are some sub routines in the descent mode that can catch one unawares.
To sum it up, I greatly sympathize with you. I have watched very senior respected grown men want to punch someone out over Airbus training. One of the biggest problems is the more you attempt to bring in your knowledge from other unrelated aircraft the more trouble you get into with Airbus logic. We have had some failure to qualify rides and all I can say is that if you are offered some remedial training do the following.
Do a mental mind dump prior to starting. LISTEN CAREFULLY to what is said and don't attempt to interpret what is being said or instructed. I had that problem on some occasions where I was trying to introduce a shortcut or workaround on the FMC that was causing my problems. Remember that this airplane was designed with the third-world in mind. It was designed to put a lot of automation between the pilot and the airplane. All the Airline Pilots in the world can drink all the beer in OZ and never finish the debate of whether that is a good idea or not. Just remember the airplane is what it is and does what it does and don't over think it.
We have had some people develop flash cards of the PFD status display and they require you to answer, "what is it doing now?" What is the horizontal mode, what is the vertical mode. When is the next vertical event, level off, speed change etc. Are there any "red balls" on the Nav Display? What will the airplane do when it crosses the next one.
Then there is the ever favorite "activate and confirm the approach mode." When does it do it by itself? What will happen now if I do it? What will happen if I don't do it? Every Bus pilot has done that one.
Attempt to know all the levels of automation and understand that this airplane doesn't like some mixed modes. We were always told that if you go manual, go all the way. Do Not leave one flight director on and another off. This will cause the FMC to go to the operating flight director and as long as it is on the airplane will attempt to follow the flight plan or last data. If you are flying the airplane, turn everything off and fly the airplane! If you leave a F/D on, it wants to fly and it will likely do something you don't want.
I could go on and on about all the idiot mistakes I have made in the Bus. I have many friends who have done the same. There is nothing so dense as a DC-9 pilot. Unless of course its a BAC-111 or Fokker F-28 pilot,( I have to two of those three so I have a high density factor), yet many of them are great Bus pilots now. But it wasn't always easy or simple. There were bruised egos along the way.
Keep the faith. Don't over think it. Many of the techniques you have used in other automated airplanes will work against you in the Bus.
Fly it exactly they way they teach it. EXACTLY! Until you figure out its quirks for yourself and develop your own style with it.
Be like the BORG and allow yourself to be absorbed.
This rant is worth exactly what you paid for it.