I'm trying to find info on how often this is, but i keep finding conflicting info. Belt changes seem to say anywhere from 60k to 100k and chain changes say 60k/150k and the life of the car. Any idea on the real answer?

Hi New to the forum and after a bit of info, just bought a 2014 1.6cdti with a snapped oil pump drive chain, Is this a common problem and any ideas what causes it, looks a bugger of a job, the owner was quoted £1800 at the garage hence selling it spares or repairs. 
any info would be appreciated
     cheers 
          Tim