The answer from Tech support was oh , we only guarantee the repairs for 3 months. You're out of luck.
My answer is incompetent repair people, lousy build quality, lack of honouring guarantees, lack of follow up, generally a buy an extended support program type of deal for which I know why*
If you have all the case file numbers you should argue your point that the repair never worked in the first place. I've had a really good experience with my 44" Z3100GP. The built in spectro and self calibration have really worked well with my printing patterns.
Of course, I got mine during the fantastic discount period ($2995!) and I went without any extended warranty. Had to replace a print head right after the warranty gave up but it was cheap and worked like a charm. I should have called when it was under warranty as the warning did pop up intermittently but that was my fault I guess.
Only used HP support twice. Once for the bad Mac serial numbers on the i1, which this forum was a great reference to give to the tech.
Second was to replace the star wheels and pinch rollers, just in case. The media scratching did show up but usually on very curled media. Counter curling helped a bit. The tech who came by was really nice, knew enough about the printers to do the job and really sounded positive about the support aspect to me.
I guess HP service in Western Canada is better than France. I got the tech's card and was encouraged to call him directly in case anything about the fix wasn't working so they would extend the case file if need be.
Whenever I read the horror stories of expired warranties and failures of the Z-series I always worry about my out of warranty printer. But other than it needing to be hard shut off every now and then (months of constant on without any print jobs), it has been near flawless for me.
Annoyances are the buggy firmware (although the latest has been OK), calibration nags, and hard to align sheets, but everything else has been great for me. I really should take better care of it (check for dust and ink overspray) but it just lumbers on without complaint. My previous printers were Epsons, which were clog monsters so if I decide to upgrade it would be HP if they offer the same kind of deal or Canon.