Just found this thing in my house.. never seen anything like it.. I thought it was a bumble bee at first then realised it was more like a fly! to be honest I was pretty sketched out trying to catch it!!! It is pushing towards 3cm from head to tail!
That can only be Tachina grossa, a huge fly, parasitic upon large moth caterpillars. It is the size of a large bumble bee, as you say, with a bare, yellow face.