Discovery 300 TDi alarm problem

Hi. I have 1994 300 TDi discovery with alarm problems - can anyone help?

The remote is unreliable at best which isn't a problem as I'm happy to just use the key to lock/alarm it. However, recently, when I unlock it with the key (having locked it with the key) the alarm goes off - not very time but getting more frequent. Has anyone come across this problem and know of a fix? Or, know if the alarm can be disconnected but leave the central locking functional?

Cheers

Niblets! great monica. have you checked battery in fob? what type of fob is it ie does the car have any stickers on car say CATS it's for stereo but affects security, OR IS IT A ROUNDISH ONE WITH 2 horizontal dabbers, central locking is a common prob search website for dramas theres loads, anyway welcome i know how frustrating it is to post with no reply..