They resume doing it now although in my case the CSR could not do it but transferred me to the lending dept where the rep could do it without issue. My sense is, if your total line with Chase is quite near the maximum it would extend, then the front line CSR could not combine / reallocate line, but either the lending dept or the recon dept reps can do it.

Also if in the past 30 days there is a line item on the card, even it is a payment, the system would not let the full line be transferred, and must keep $500 or whatever amount on the canceled card. The lending dept rep told me.

Citi on the other hand, remains steadfastly refuse to do it.