pappabagge
I don't know if I am misreading your post, but the pax should not need to speak with the tour operator in this instance.
If the tour operator (A), who is the principal, oversells the flight, then the operating air carrier (B) must apply the denied boarding rules and pay the compensation to the passenger within 7 days.
B then has a claim on A to recover their outlay, but the passenger is out of the loop.
Post 15 explains.