I'm traveling DEL-LHR in a few months on a 789. Expert Flyer shows almost all of row 30 (exit) blocked on most dates. However, on some of the dates there are occupied seats in row 30. As a OWE am I able to request an exit seat be unblocked in advance? I searched the BA board but didn't find anything definitive. I'm very tall so I'd like to know my options.