score:9
It seems reapplying is one option. Since rebooking the flight is much costlier than reapplying , I am going to reapply.
EDIT :- I reapplied following exactly same procedure as I did the first time. Got a call from British Consulate , NY as to why I am applying again when I already have visa. I explained the reason and that person was okay with that. Got approval email a couple of hours later. My UPS package has already started from there and should be here tomorrow morning.
In the end, saved more than a grand! It was worth the effort.