Amazon's murky world of one-star reviews

Amazon's marketplace is being abused by independent sellers using one-star reviews to harm rivals, the BBC has been told.
Newsnight spoke to a number of those affected who believe their sales have suffered as a consequence.
A consumer rights champion now wants a UK watchdog to investigate further, as part of a probe into fake reviews that is already under way.
Amazon claims to be "relentless" in tackling review manipulation.
Even so, some of those targeted believe it cannot eradicate the problem.
Third-party vendors have sold more physical goods on Amazon's site than the US tech giant itself every year since 2015, according to its own figures.