Blocked
Is this really so bad? If I am desparate to get a word in on a really busy, SE UK frequency and the controller's transmission is blocked by another I don't want the controller to wait until sure no reply is going to come, leaving dead time I cannot interrupt (but a newcomer on the frequency might unknowingly do, and extend the confusion and jump in where I am waiting politely). Why not someone just say that the transmission has been blocked and is not going to be acknowledged, so the call can be repeated? Why is a callsign needed?
I accept there might be a downside to this, and so have never called it myself, but it has always been useful when I have heard it
Descend FLXX0, turn right heading XXX, report that heading to AB Control on 1xx.xxx
To turn it onto the controllers, this is one of my pet hates. If there is a junior pilot on the radio and the captain is busy, or if there is only one pilot in the aircraft (or on the flight deck at that time) then multiple instrctions are tricky but not too bad. Multiple instructions and a frequency change are really hard. It wastes air time if we have to check the frequency or if we get something wrong. At worst we could read back and note the wrong level or heading, then change frequency before you can correct it. I know we're supposed to wait, but we all know we sometimes don't especially when busy rebriefing for an approach to the new runway, say.
timelapse
I hope I never have to fly with either of them! Even the PPL cannot be excused that sort of stupid behaviour, except that he was presumably not captain.