Help - bonnet release catch stuck!

[AlexH]

Went to top the oil up this morning and the thing won't budge an inch, so the bonnet is staying firmly shut!
Frightened of pulling too hard in case the bloody thing comes off in my hand!
Can't find anything about it in the bible.
Any help greatly appreciated.

Edited to say: Got the bastard thing open...but now it won't close...

>>> Edited by AlexH on Sunday 3rd August 10:47

[AlexH]

Cheers Joolz, given the whole thing a thorough going over (think the problem was both ends) and seems ok now. Not being able to get your bonnet open ain't funny though!