Great story, Declan.

The first time I ever sang with a mic I worked up the nerve to do Hong Kong Blues. And it went well until a guy on the stage with a mandolin started "helping me out." He revved up the tempo, dumbed down the phrasing, until finally I got so distracted I tangled up in some tricky chords at the end. Grrrrr.... So I agree, if you don't want "back up" be sure and say so.

On the other hand, as someone rightly pointed out, session playing is about communal music making. When singing on my own I tune my guitar down a bit to match my voice. But I always tune "properly" before arriving to play with others, and then make sure I'm in tune with them, as I don't use an electronic tuner. Even if this puts some songs out of my range, I can still harmonize, or just play rhythm.

Mr. Happy, it sounds to me like going off in a huff was the best thing this fiend could do for you.