Were able to close a card via workaround SM end of the year and another card yesterday - both showed closed when I logged back in a few hours later.
Chat remains the best way to reduce CL as it is done thru the chat while the workaround SM would take several days.
Personally I would use SM to
1) request match (need to give a few days before hearing the outcome, 2) close account.
But I would use chat to reduce CL.
Both are painless,