FlyerTalk Evangelist and Ambassador: The British Airways Club
Join Date: Jun 2008
Location: Somewhere between 0 and 13,000 metres high
Programs: AF/KL Life Plat, BA GGL+GfL, ALL Diam, Hilton Diam, Marriott Gold, blablablah, etc
Posts: 33,177
I think that with 13A and 14B unless there is a really exceptional situation whoever seats in 14A will likely be happy to move to 13A (unless they are superstitious in which case ask the 13B person!). Just ask politely or ask a crew member to ask for you and explain.
Note that it is also possible that more seats will be available at OLCI so just try to check in early and if it failed you can ask again at the airport if there is any window seat pair left.
You should definitely send an email to BA to explain that you are disappointed by what happened and ask to be refunded the cost of your paid seat selection.