Originally Posted by
Grouchy
Flight may have been full or you showed a Delta BP?
Otherwise it's no problem and if you show up early enough KLM agents check and ask if you would like to take a earlier flight even up until like 30 minutes before the flight.
2nd options is just do it yourself or let show an agent the 'tariefvoorwaarden' when you pull up your KLM PNR and trip:
Wijzigen na vertrek: Wijzigen na vertrek van de vlucht is kosteloos toegestaan.
In more than twenty-five years of connecting through AMS regularly on M class tickets, I have never been offered the option to take an earlier flight. Only once did I manage to changes, and that was after IROPs where my rebooking onto the exAMS connecting flight was somehow done inconsistently.
However, I always have tickets issued by PMNW and now DL, so could that be the difference? Sometimes the KLM operated flights are NW/DL codeshares and sometimes not.