After the EOL calibration fails, go into the sensors tab of AD and select the 'error' sensor (I forget its exact name, but it's fairly near the top of the list - have a hunt for it before you start the EOL routine, so you know where it is). Clicking on the 'start monitoring' button should reveal an error in the 'value' for the sensor.
Most garages will charge you a lot of money for a new actuator/gearbox/both. They only do this because they don't understand the system, and it's the easiest (most profitable?) option. In reality, there is usually a small component that can be fixed/replaced for a fraction of the cost.
There are a couple of people who spring to mind that could help...but they're not (that) local to you...
Now that you've got AD, have a look under 'sensors' for 'hydraulic circuit pressure'. Monitor that with the engine running, while you try to change gear. It should stay between 45 and 55 bar. Also see how well the pressure holds up when you're not changing gear. That should give us a few more clues.
The other one that I find useful is 'position of insertion fork'. It should be a nice square wave as you change gear (with netural being at the centre point on the y-axis).
Try those and let us know how you get on
EDIT: Additional thought - have you tried reading the Sele ECU fault codes in AlfaDiag? That might provide a hint too