stove and chimney question

So my wife and I bought a house last year which was built in 1976. We recently replaced the old wood stove with a pacific energy vista with a 6 inch stove pipe whereas the old stove was an 8 inch. The stove sits in an open fireplace and when they installed the vista, they used a 6 to 8 inch adapter but found the chimney pipe it was supposed to attach to was too warped and rusted to use, so they just removed it. The adapter now just sits in the middle of the old vermiculite insulation and they replaced the firestop and used some fireblock foam to try and seal it off. So there is essentially 4 feet of missing chimney pipe at the bottom of the chimney, where the smoke leaves the stove through the 6 to 8 inch adapter and goes through the vermiculite where the 4 feet of missing pipe was. Also, looking at the top of the 14 ft chimney, it looks like stove pipe instead of chimney pipe, insulated with vermiculite. I know that's not ideal but I'm not sure how much it would cost to fix.

Anyway, we used the stove over a week ago just one time, and every since have had a smokey smell in the room. It isn't there in the morning when it is still in the 40's but it is obvious later in the day when it warms up. It is particularly bad in the fireplace above the stove. I'm still new to this, but it sounds like poor draft and maybe a poor seal from the firestop above the stove.

I'm not sure what my options are, but was thinking I should either replace the firestop with a more custom fit one as opposed to the poorly fitting 2 piece one currently in use. I was also thinking I should replace the missing section of pipe with chimney pipe and have the adapter connect to that. I originally wanted to do a flexible 6 inch liner but I'm not sure it will fit in the 8 inch pipe after being wrapped in insulation.

Sorry for rambling, I hope it makes sense how I explained it. I can upload pictures if it would help. I'd like to get this fixed sooner than later as I have a young kid and a pregnant wife and don't want to cause them any problems. Also, still waiting for installers to return my call. Thanks in advance.

Thanks for the replies. Would just replacing the missing chimney pipe with a section of 8 inch rigid liner be an acceptable solution? I'm just not sure a flexible liner would fit inside the rest of the chimney as there are screws sticking out of the pipe at the top of the chimney and I figure there are probably more going down the chimney as well. I suppose a good chimney sweep could use a camera though.

Thanks for the replies. Yeah, I'm not too happy with the installer. Do you think just replacing the missing section of chimney pipe with 8 inch rigid liner would be acceptable? I only say that because I'm not sure a flexible 6 inch liner will fit inside the 8 in chimney pipe as the top of the chimney pipe has screws poking through into the pipe, and I assume there are more screws down in the middle of the chimney.

I appreciate everyone's advice and feel as though the best thing will be to start over with the chimney as it is likely problematic throughout. I am aware of older vermiculite and asbestos and would rather not have that in the home. To answer a few questions, yes, i do think all the remaining pipe is equally thrashed as what was removed. It is a full masonry fireplace and chimney with what looks like a stove pipe liner with vermiculite around it. The issue I think I will have fixing it is that there aren't many options as far as companies to service it as this is a relatively small town. Using the resources posted by begreen, the closest CSIA resource is over 6 hrs away. Locally, there are one or two chimney sweeps who do it on the side, and then the company that I bought the stove from. I still need to get ahold of the owner of that company to see what he can do for me. Would a construction company be able/capable to work on it if there are no other options?