Spending ages on the phone spelling out what you want and waiting for them to find it is a complete waste of time, both yours and the phone agents. Just email in the itinerary that you want, with classes and fare construction, someone can then just copy it exactly to construct the booking correctly. They will email you a PNR and you call up to pay (and apply GUF/UUA etc). The person dealing with emails is dedicated to that task for the day, doesn’t take phone calls, and can get someone to else to make the booking if they are free.