Hi, just seen these in Pirin national park (today, 13/09/2017) in south west Bulgaria, at about 2100 m altitude. They may or may not be different birds. I thought at first that they were definitely apline accentors, due to the location and the yellow on the bill and that they didn't seem like the dunnocks I see every day, but then they don't seem to have the red-brown steaks, and it's not clear if the neck is barred or not (on the first two anyway). I didn't try to remember their calls, as I didn't think they could be dunnocks until now...
Thanks a lot,