Cheers for this thread - incredibly useful! I had four Finnair flights (BA codeshare) as part of my overall BA booking, and wasn't able to reserve seats online. After consulting ExpertFlyer, I sent off my list of four seat requests to the FinnairHelps twitter handle - within two hours they had sent a message back confirming reservation of all my preferred seats. Excellent stuff - and can agree with @
bisonrav that they're very quick, efficient and friendly!