For transfer CL at closing, I always call. Sometimes the front line agent can readily do it, sometimes they cannot (system wont let them) and they have to transfer me to a specialist and s/he then needs to look something up and then do it with success. I was told if the card has any activity, even a payment, $500 must be left on the closed card. If the card is inactive the past 30 days, the CL could move in its entirety. Though in reality, it seems $500 is always needed to stay with the closed card.

I have tried the SM method and they always come back to tell me to call.

Also, closing a card with Chase seems to return the credit to your "pool" in just a couple months.

Lowering credit line voluntarily, does NOT return the excess back to your "pool" for a very long time. Two approaches can have a drastically different outcome. The explanation given, was that if the cardholder lowered the line himself, means the cardholder did not need the excess credit and the bank should not issue the excess again - it is probably part of the interpretation of the recent legislation "Know Your Customer" that makes banks paranoid.