Hi hoping for someone to shed some light on an issue I have. 

I’ve found that my handbrake is variable in working. Sometime it clicks 4-5 and hold car fine, and then (even on same journey) you can pull the handbrake up all 12 clicks and car still isn’t held. Then it returns back to normal operation on next use.

I’ve adjusted it according to haynes manual - using shims at callipers to ensure it’s not overtightened etc.

It’s MK3 focus (2011-) with Z shape handbrake. Pads and discs in rear - all fine with plenty of pad left.

I know it has auto adjuster somewhere (?on handbrake lever ?in calliper) and wonder if they’re faulty?! Or if it’s just needs finer adjustment. 

Ive taken to a 3 garages (national companies all proclaiming to be brake specialists) - one said its fine (it’s clearly not), one said cable needs replacement (but doesn’t seem so when adjusting as per haynes manual) and the other said to rewind the piston to reset the ‘pins’ but they can’t garantee a fix and will charge a handsome price to try.

Does anybody have any experience with this? Seems like no nobody has a clue.

Sounds like one of your calipers requires replacement. Next time it ratchets all the way up , leave the handbrake on and check under car and see which caliper arm  the cable has pulled up the most. That will be the caliper to change. 

Sometimes you can replicate the fault just by repeated handbrake operation, may take quite a few goes.