Help with B5 Passat central locking

[Flat6]

The 12v battery on my 1.9TDI Passat is at the end of its life and has been draining if left standing for more than a couple of days.

Last week it was left several days and flattened to the point where the doors wouldn't unlock, so I had to use the key in order to get in and open the bonnet to put on charge.

Since then the central locking only opens the drivers door, and the second press of the button which would normally unlock all the others, doesn't.

Any ideas how I can fix this? The other door locks are all functional as they will open using the unlock button on the inside of the car. Its just the second "plip" of the remote which seems to be the problem.

[TooLateForAName]

does the central locking work at all?

The a4 used to have a pump which failed and was expensive. Is your passat the same?

[Flat6]

Yep, locks all the doors fine, and they will all open on their own if the internal central locking button is pressed. The problem is only when trying to unlock them using the remote, it only unlocks the drivers door (even with the normal two presses of the button which normally unlocks all doors)