Hidden in the depths of the Alfa155 archive I found the programming procedure, thanks to Simon and Wrinx

Just thought i'd chuck it in my post to put it at the top of the list for Umesh & myself.
This is a copy of reply I sent some time ago to a similar problem. It looks at though you may have upset the alarm receiver which controls the central locking (it may have lost its memory). Does the alarm still arm OK? (The main alarm unit is not part of the central locking):
I take it you have 2 transmitter keys. First (blindingly obvious) check the
alarm is switched on, the switch is in the glovebox.
Now sit on the rear seats and look up at the roof receiver (its in the rear coutesy light). Hold the key nearby and press the button. If you see a steady green LED for about 2 secs then the roof rx has recognised the key. Under normal circumstances the
central locking would cycle and the alarm would arm. If you see the LED but
there is no reaction, then you would appear to have a wiring problem between
the roof Rx and the rest of the vehicle.
If however this doesn't happen, then you can open the memory of the roof Rx
using the the key code. The code should be a 4 digit number. CAUTION, I'm
not sure what happens if you get any of the following wrong.
First ensure that the alarm is turned on at the glovebox.
1. Press the button on the Rx for approx 2 secs. The LED should flash for
the whole time you hold the button.
2. Release the button. After approx 2 secs the LED should flash once. This
is a request for the first digit.
3. Press the button the number of times corresponding to the first digit, ie
if the first digit is 4, then give 4 presses. Every press should cause a
brief flash.
4. Approx 2 secs from the last press, the LED should flash again to request
the second digit.
5. Continue in the same way for the other 3 digits. If a digit is 0 then
don't press at all, just wait for another request flash.
6. Having entered all 4 digits, the LED will either stay oncontinuously
meaning that either there has been an error entering the code, or the code
is incorrect. Or the LED will flash, meaning that the code is good.
7. At this point if the LED is flashing, hold the rx button down and press
the tx button.The rx LED should light continuously if the code has been
memorised.
8. There is a country setting procedure that follows but I'll omit this as
it defaults to EEC so don't do anything.
9. The rx LEd should now flash 6 times to show all is OK. If you get 18
flashes start again from point 1.
10 Repeat for key 2.
If you do not have the correct code, check what the National Security Agency
have on record, (that the sticker you should have on the windows, or a
dealer can check for you), as they are given all the key and immobiliser
codes at the time of importation.
If none of the above works at all, then you are looking at a new roof rx
(£90) and 2 or more new keys (£50 ea) plus fitting and programming. If this
happens to be the case, then you should be aware that then another similar
programming procedure applies, further details on request!
Hope that helps.
Simon"