Constant alarm beep (mk3)

[AnToNy]

Hey guys,
I've got an issue which I simply can't fix yet I've tried everything I can think of.
My alarm sounded the other night not looking good after coming home, so I went out and reset and checked the car and all was good.
Now however, whenever I lock the car or allow it to lock itself the indicators flash twice as usual but the alarm sounds a constant bleep for about 30seconds.
I've checked and greased all locks on the doors, boot and bonnet.
I've had it on my code reader and no faults are there.
I've checked the wiring to the bonnet catch and all seems fine.
What else can I do????
I currently let it sound off knowing it's locked or leave it unlocked.
Help

[AnToNy]

I've disconnected the wire loom to the bonnet sensor and all seems normal now.
Guess I need a new catch or maybe take it out and give it a good clean.
Is it easy enough to remove?