I have booked a SMART fare flight through a third party. I was able to assign myself a seat after booking on the EW website. Now I would like to change that flight to a later date. When I look up the booking on the EW website it explicitly gives me that option, I select the desired new flight, it says "your flight will be changed". Takes me back to the booking overview, only to display the original booking. I tried different web browsers already. Any idea how to resolve this?