If you're not getting what you're paying for, stop paying -- and then request/demand a refund for the affected time-frame.
Pinboard is a one-man shop and maybe that one-man has some personal life issues of some sort to deal with. Adjust your expectations accordingly, going into the future.
If a service you want to use is a one-man shop, adjust your expectations accordingly.
(Please in no way take this as excuse-making for idlewords, but rather as a rule of thumb.)
PS: Who runs Raindrop.io? It looks like a one-man shop, but I cannot find who that person is.
Edit: Looks like this fellow runs Raindrop: