In an email exchange with city staff regarding the previous post about missing rings from bike lock-ups, staff have told me the number to call regarding issues with ring-and-posts. I am giving it a full post (instead of commenting on the previous one) to disseminate the info widely:
The post-and-ring line is 416-39-CYCLE (392-9253).
(If you call your councillor, they’ll just forward the query to this office anyway).
Apparently the rings are sometimes taken off temporarily for photo shoots, sidewalk maintenance work, or other similar reasons.