Disco 1 Central locking problems !!

Hi all.
Anyone out there with knowledge of central locking .??? I have a 300tdi 1998 and have been having probs with the locking and unlocking of the car ,,most time i need to be within two inches of the car before it will lock or unlock,,have tried new battery in fob but that has not helped ,have tried just to lock it with the key but still need to use the fob before i can start the car as the immobiliser is still on and it can take up to 15 seconds or so for the fob to work even standing right next to the car..
Any advice would be greatly appreciated ..thanks

Clean the battery contacts in the fob

The charge condition of the vehicles battery can have an impact in the range the remote central locking works, but if your having difficulty with remobilising the engine with the fob when it's placed near the ignition switch suggests an iffy fob, unless the u have the same issue with your spare fob.
Fobs can loose their tune according to Remote Key who will refurbish your fob.

The receiver can have a weak earth or contacts in the plug too or it's simply "tired"

Hi Aleric I had the exact same problem with my 1998 300tdi, I bought 2x new key fobs from ebay LUCAS 3TXB they cost around
£26 ish each plus £6.00 for next day delivery and I had automotive locksmith program them at my home he charged £80.00 cash well worth the money
as all related problems were immediately cured I hope this helps, regards from Madman2Swords down here in Bristol.

Hi to all .
Thank you for the help and advice ,,my disco has done almost 200k so maybe its time for new fobs ..
Thanks again to all .
regards