No Longer fit for purpose

Over the years a lot of my purchases have been from amazon based on the number and quality of reviews.
It is always useful to get other persons insight on a product which has helped make some steller buys
Amazon has always been much better than the rest but recently this has got to the point where it no longer works
Recently I was after a car heater for my van and did a search
All of the top items had 100% five star reviews but on closer inspection a lot on different sellers where identical and all done in 24 hours
Really makes a mockery of the review system and Amazons ability to control its marketplace