They asked a permission and for me to fill a form so that they could remote connect to my NAS, and after investigating gave me on the support chat/list thingy the commands that they thought would fix it but they wouldn't run them themselves. Ended up working (issue was that a power failure happened during a shr2 reshape, and while the lvm volume had recovered mdadm hadn't and was blocked in a failed reshape loop, since it was a mix of mdadm and synology's own shr2 [which uses lvm to achieve its goal] trying to find help on the internet was next to impossible, which is why without them I would have wiped the whole thing).

Was as a personnal customer and no paid support (beside having bought the product of course), within the second year of my purchase. Overall I've had a fair amount of support requests with them for my personnal NASes and the couple dozen I manage for professionnal purpose, and I'm very happy with that relationship.

PS: my original support request was very detailled though, I did not just go and ask "doesn't work, fix it !"