today i got a 404 error when i go to the shop page. once again, clear cache, purge sef urls. I do this about 3 times a day now.

We could probably handle URLs with empty variables, but the ones with wrong values like product_id=145.html are really strange. Try enabling the URL Source Tracing in JoomSEF's Advanced Configuration - that way the source information will be stored with new URLs, so you can check where are they coming from.
Also when you purge the URLs and they're created for the first time so the website is working, you can set the correct shop.html URL as Active - that way even if duplicate URLs the one you selected will always be used.

can you please check my previous two or three posts as well, maybe this is all related to one bug.

i've got clients emailing now that they can't find products on my site because when they click on certain things it takes them to other places.

I need to disable this extension (WHICH I PAID FOR ALMOST 4 WEEKS AGO) again.

I was referring to all your posts with URLs screenshots.
Anyway, we've just released an updated version of our extension, which should stop generating URLs with empty variables and URLs to non-existent objects, thus eliminating the duplicates. You can update it using Manage Extensions page in JoomSEF. Make sure you purge your SEF URLs and clear Joomla and JoomSEF caches afterwards.
Please let me know if it solves your problems.

thanks. i've installed it now and will keep an eye on it. will keep you up to date.