office 2016

Does anyone know the best (cheapest) place to buy a licence key for Microsoft office? Just read some feedback on amazon and apparently there are sellers selling stolen corporate Microsoft office licence keys, some people are paying for a key they can't use and others are having their software...

A client has had her laptop borked (possibly from an update to 1709). I have tried all the usual to recover from a black screen with cursor after login, safe mode, safe mode with command prompt. The laptop is an Advent X700 (windows 8 upgraded to win 10). I have recovered her documents folder...