Official comment

Antoine,
Unfortunately the power adaptor is not covered by warranty unless it is DOA (dead on arrival), as we can't guarantee that the wall power our customers are using isn't subject to overvoltage / undervoltage / spikes / etc, or negligence causing damage to the cable, all of which are beyond our control and not due to a manufacturing defect.
I'm sorry this is a difficult item to replace, and I agree with you -- it's not an off-the-shelf part, it's really expensive, and as you can really only get it from one parts supplier, if they're having issues with stock, it's a problem for everyone.
I'm also sorry about the issues you've had with support, I'm not sure why you were hung-up on (or by whom; we use a call centre to generate tickets and they're supposed to handle that correctly). I've looked at your ticket with Luana, and she's provided the same information I would tell you here. I'll dig into the parts availability issue with PacParts, but unfortunately this is not something we can provide for you as a replacement.