While driving with my window could hear a tinney noise coming from the osr area of my 2006 td6
I thought it would probably be the rear disc back plate so today I’ve removed the osr wheel to inspect it.
Obviously is very rust with a home at the bottom but I also found these 2 items trapped at the bottom between disc and back plate

Click image to enlarge

Ahhh, what you have there Sir, are the components that hold the hand brake, brake shoes in place. You will have to open it all up. From what you have said, the hand brake unit brake shoes must be binding, I would investigate this sooner rather than later.

See below link for Rimmer Bro's video on changing the hand brake pads, for the location of the bits you found.

Great thanks

Can you buy that part separately or the whole handbrake mechanism?

Yes you can get them separately, see below link, these can become loose due to the hole in the backing plate being enlarged due to rust.

As you have just had new brake parts, I am surprised that this has just happened, if it was at a garage this should have been sorted out then.

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If the hole has rusted in the backing plate, then rather than replace the backing plate you can use brake retainer cup washers - https://www.bimmerforums.co.uk/threads/e46...avy.64462/ will give you the idea. There's a writeup on this site somewhere as well IIRC. Note that there are different size cup washers for different brake manufacturers - might need to try a couple to find the right one.