Thanks, all. In my case, departure time was not compromised in so far as I could get to airport, etc. However, I do have an update:

Called to cancel and was told mileage would be redeposited minus 3k and surcharges minus $25 telephone booking fee would be refunded to cc. I inquired about the schedule change and keeping the 3k. CSR put me on hold, came back, and said that since I had not yet "approved" schedule change (received a voice message a week ago) then yes I could keep the 3k.

A few minutes after hanging up, my balance was -3k, but today it is back up with the 3k added. Received email that full surcharge fee being credited to cc. It's possible actual refund will be -$25, but as of now they are also refunding that.