BOAC
One must remember (read the small print) software (ms) is not covered by UK Trading Standards Law. There are 'get out' clauses when the original product e.g..laptop is purchased. OS do not come under the guarantee. Only the hardware is covered.
Having said that, if one purchases a flight sim from a major supplier (packaged product) then yes one has the recourse to return it to the retailer for a refund/exchange.
The trouble with OS/M$ is that people do not read the 'terms and conditions' before hitting the 'install' key.
Daz