The car emits very loud beep after about 15 mins lasts c 20 secs. After I recorded it the garage have said it is part of the alarm system. So to fix disable alarm has any one else had this problem? How fix

 

Find the actual problem and fix it, as disabling the alarm is not really either wise or doable.

So far the garage appear useless - I'd either DIY or find someone not clueless.

 

This could well be the passive secondary alarm box making the bleeping.
It is located in front and below the engine compartment fuse box.
I think that there are a couple of rechargeable batteries in this unit that can fail, also water can get in and mess it up.
This can also start to play up if the main battery is starting to fail and lose its charge.
The unit can be disconnected and doing so will have no effect on anything else, but I think it will keep making a noise until the internal batteries go flat!

Be warned it is hard to get to.

Mellow

 

Lots of info here:

https://www.jaguarforums.com/forum/s...02-how-189612/

Post #2 has sound clips of the two alarms, so you can confirm the source of the noise.