So Dior USA wouldn't offer an exchange (although I did speak to a lovely SA named Rosalina at The Mall in Short Hills NJ which I HIGHLY recommend), but Heathrow airport is offering new handles free of charge! Phew - I'm so relieved. Now I can finally use it! Note to self: never buy a bag not in person at the airport again!
Late to the thread, but glad to know that the handle saga is ending in a happy manner. Congrats on that gorgeous pink LD!