Multi-turn user requests:
user: I'm on a quest to escape my quaint hometown of Oakendale for the dynamic allure of Los Angeles! Eagerly anticipating this journey, I need to arrange a flight on the 15th of next month, which is November of 2024. I’ll be using my reliable credit card represented by 'crd6789' and token 'abc123xyz', to reserve a seat in business class. I expect this venture to cost approximately $200. Could someone handle these travel arrangements for me, please?
user: With the excitement of my flight secured, I'd feel more at ease by getting travel insurance for $50 under a specific plan. How about using the same credit card and token for this? And, hopefully, we can link it to the flight booking?
user: The plan is 'comprehensive protection'.
user: My notorious forgetfulness strikes again! I cannot recall all the specifics about the flight and insurance I just organized. Would be great if someone could retrieve the invoice from my latest transaction to ensure everything is lined up properly.
user: An unexpected charge popped up on the invoice that I retrieved. If at all possible, could someone contact customer support with the details to hopefully solve this issue?
user: Customer support didn't quite resolve my concerns, and now I'm a bit frustrated. It would be appreciated if a priority-2 ticket titled 'Billing Concern' could be initiated, incorporating the detailed exchange with customer support, so we can escalate this appropriately.

Ground-truth function call sequence:
TravelAPI.list_all_airports
TravelAPI.get_nearest_airport_by_city
TravelAPI.book_flight
TravelAPI.purchase_insurance
TravelAPI.retrieve_invoice
TravelAPI.contact_customer_support
TicketAPI.create_ticket