the report also raises a fundamental CRM point. On Page 3 it says "... the co-pilot started to action the QRH ........ He also continued to operate the radio". I think that is a bad move and is a recipe for incomplete checklist procedures and possible disaster. To try to action the QRH and deal with ATC at the same time is likely to be a very bad move and so it proved. He was rapidly being overwhelmed.
In my last company, it was SOP that when something went wrong, the call was:
"My aeroplane, My radio and Your checklist".