get hold of, get a hold of - either way would do

Checked the discussion here:

http://forum.wordreference.com/showthread.php?t=120123

Can't say one is right, the other wrong. Yet the native speakers are debating.

Since your boss picked it up, whatever she said is right, do not argue. Seems you are very lucky to have a boss paying so much attetion to the details.

To avoid such kind of attention, always check spelling before sending anything out. Be articulate, use formal, written English, avoid idioms or slangs.