Multiple users are now reporting that gift card PIN codes are simply not working.
I reported this issue here in the community on April 16, after I was unable to resolve the problem through Twitter with @SpotifyCares. Here is a link to my post from April 16:
@sebbsher reported the same problem today, in a new thread:
He said he bought twelve cards and none of them are working.
Other users are reporting the same issue in a different thread, in Spanish. This thread began on March 24, and has reports from three different users:
Spotify needs to wake up and acknowledge that this is an ongoing issue, and take immediate steps to resolve it. And for God's sake, moderators should stop copying and pasting links to the standard help pages, because those steps do not resolve this problem.