Think I got a bonnet catch letter today too (I've been told a recorded delivery letter came from Renault, I hav'nt been home to open it yet!). Surprised they've sent one now, this issue came up ages ago! Got a feeling I've already had a letter before but not can't remember 100%.
As it happens they 'fixed'* it for me when it was in the dealership for some other work months ago. Looked fine (no corrosion) before they did this anyway.
*As in smeared the catch and surrounding slam panel in grease. Lucky I'm not too fussy about engine bay cleaniness/appearance!