Seems, it was a mistake.
Archiving stopped around 85% of my bookmarks.
I've had those problems before, especially when the owner played U.S. politics and didn't care much about Pinboard anymore. I still went back.
Pinboard's support doesn't reply to mails, Pinboard's Twitter account doesn't reply, either.
I've asked for a refund (within the one week refund window). No reply.
Maybe he'll reply here. Last time I had such problems he also ignored my mails for a long time and finally replied on HN.
People, look at Wallabag seriously. Maybe Pocket. And maybe Archivebox (https://github.com/ArchiveBox/ArchiveBox).