Originally Posted by
stevendorechester
One advantage of buying a DL ticket is that they apply their COO on codrshare flights.
OP should file an EU complaint for both IDB as well as any delay and duty if care. EU laws do not require the plane be oversold. The passenger paid DL for a ticket and was denied boarding.
Also, a chargeback should be in order, only for what was not provided though and not the full amount.
EU regulations apply to the operating carrier of the affected flight, not the marketing carrier or who sold it. The issue was
Transavia and who the OP would need to pursue for a EU claim.