Edgee,
I think you got a new, not-fully-trained rep, because I believe what you were told is incorrect.
If O offers a 14-day cruise (Called, let's say "Fabled Seas & Antiquities") from Rome to Istanbul, April 27 - May 11, 2023, and that's the cruise you book, then you only booked 1 cruise, 1 down payment, and 1 cruise credit.
The fact that O also offers a 7-day Rome-Athens ("Charming Italy & Greece"), 4/27 - 5/4/2023, followed by a 7-day Athens - Istanbul ("Turkish & Hellenic Gems"), 5/4 - 5/11/2023, has no bearing on the cruise you booked. In fact, if you tried to book the two 7-day cruises in order to get 2 cruise credits, O would not let you do it and would instead book the single 14-day cruise. I know this because it has happened to me.
You should receive a single booking number for the 14-day cruise. You will also be charged considerably less for the single 14-day cruise (with 1 deposit payment) than you would be required to pay for the 2 7-day cruises. Taking a PH1 as an example, the 2 7-day cruises are $5,199 and 5,099 respectively, while the 14-day cruise for the same PH1 is $8,400.
You need to go back to O and ask to speak to a Supervisor, or Manager and have this corrected in your favor.