Bissell 3920 Bagless Upright Vacuum

The Bissell Pet Hair Eraser immediately took off the top layer of our carpet, but I figured it was ok- it was new, cheap apartment carpet.  After about 3 months of doing a far job, it lost 50% of suction, and began to leave black marks on our carpet. I cleaned the bottom of the vacuum hoping this would remedy the problem, but the marks continued to show up, especialy when I used the hose attachment.  I have maintenanced the vacuum, replacing the belt and filter (which in owning it for under 7 months seems like a failed attempt at salvaging an expensive buy). None of these things improved suction or got rid of the black marks on the carpet. It picks up small pieces of dirt, but ironically, even the attachments don't pick up animal hair :/. The hose attachment continued to work well throughout the vacuum's life, despite our problems, however, with all of the strange, plastic animal hair attachments that were included, there were no small attachements that allowed one to get into corners and small spaces, so I had to brush the sides of the walls and furnite with a brush and then use the hose attachment, basically making more work for myself.  I have had to throw this expensive vacuum cleaner in the garbage.  Our carpet is absolutely ruined- it is torn up from the brushes and heavy rollers, marked up with black marks, and still has ground in hair.  I have borrowed a 40 dollar bagged vacuum from my sister in law that got me through until I could buy a new cleaner that worked better than this cleaner.  The Bissell Pet Hair Eraser seemed like a product that was mostly for show, that didn't hold up to it's promises. I do have 7 cats, however, they are all short haired cats, and when my sister's ancient bagged vaccuum sucks up their hair better than this $120 dollar procut, there is obviously a problem.  My advice is to go with quality, not frills!