I found the Premium Service Line was busy, most of the time. First time I managed to get through, the agent said he couldn't hear me (I was on a landline). Second time I got through, I was forwarded to a disconnected extension. Very poor service.
So yesterday I tried the online chat on the web site and requested my itinerary to start and end in MAN. More flights to AMS per day, more flexibility.I supplied the flight numbers for my preferred itinerary.
I *think* this has gone through. Some changes have popped in My Trip. But it also lists my old itinerary. And I haven't received an updated ticket, yet. Maybe the back office only works Monday to Friday. We'll see next week.