Unauthorised RT in KOS
On departure from LGKO, (KOS), and restricted to 4000ft due to inbound traffic at 5000ft, on the SID.
One male ATC controller on duty ( I assumed), and the inbound was on TCAS, with restriced procedural descent, due to our departure.
Then an authorative female voice, (greek sounding), passed the instruction A.ABCD climb to FL90, just after we reported level at 4000ft.
Because it was so obvious that a) this was a stupid, and b) not a ATC request, was ignored.
However it happened, and could have caused an accident.
Beware,
heated.