Plane changes to IAD

Hello all
Can anyone tell me why my flight to IAD in August keeps changing? When I booked last month VS21/VS22 was a 340 (as expected). Two weeks ago VS21 became a 346 and 1 day later it reverted to a 340 again. Today VS tell me it is now once again a 346 and have again changed my seat bookings to reflect the change to suites.
As I haven’t used the suites yet obviously I was excited at the first change. Then mildly disappointed at the quick about-turn. Then again today quite excited. The trouble is I’m too old for this roller-coaster ride of seat-changing thrills…being the sort of person who checks everything a million times before departure, I can see I’ll get nervous exhaustion if they do this any more. [:I]
I know planes change for operational reasons on the day but why all the chopping and changing? Are they short of equipment or something? Is this happening on other routes or just DC? [?]
Can anyone tell me why my flight to IAD in August keeps changing? When I booked last month VS21/VS22 was a 340 (as expected). Two weeks ago VS21 became a 346 and 1 day later it reverted to a 340 again. Today VS tell me it is now once again a 346 and have again changed my seat bookings to reflect the change to suites.
As I haven’t used the suites yet obviously I was excited at the first change. Then mildly disappointed at the quick about-turn. Then again today quite excited. The trouble is I’m too old for this roller-coaster ride of seat-changing thrills…being the sort of person who checks everything a million times before departure, I can see I’ll get nervous exhaustion if they do this any more. [:I]
I know planes change for operational reasons on the day but why all the chopping and changing? Are they short of equipment or something? Is this happening on other routes or just DC? [?]