Furious with my chimney installer

In this case, it was the owner / sole proprietor, who did the install. This guy is dead honest, as far as I know, but he's very sloppy. I'm sure he doesn't even see the problem with what he did, and wasn't trying to screw me. There's just no dealing with folks like that.

I guess I should've asked before ordering! However, I think my plan will work out okay. I'm putting an appliance adaptor on the bottom of the flex liner (perhaps cutting off the 2" of crimped area on the liner), and attaching a single-wall telescoping pipe to that with screws. To clean, simply undo telescoping pipe at stove collar, slide up, and send the sooteater up there to do the dirty work.

One question I do have, though... this old F12 has no screw holes or anything in the stove collar, to keep the stovepipe attached. My newer F12 has Jotul's typical (but senseless to many) setup of two tapped holes with bolts in them (M6'ish), for which you must drill the stovepipe, so you can run the bolts in to hold it all together. I'm thinking the best plan here may be to drill a couple of holes thru the stove collar big enough for a couple of stainless self-tappers, to run into the stovepipe. Opinions?

yes i would drill the stove color to accept your screws

Doesn't sloppy and fire somehow not really work well together?