Almost certainly the former. I have a similar problem, albeit with a Classic Award, coming out of South Africa next week. I want to try and change my departure airport from CPT (from where there are no flights) to JNB, and then on to LHR instead of NWI - this being the only way I can bring my departure date forward by a day.

KQ shows availability on every day in September via NBO. Some FB agents tell me the flight is available, some say it isn't (so what's new?). FB Canada tells me that I can only re-book the flight at a KLM ticket office (ie AMS). They really must be completely mad if they think it's practical for a customer to do this ...

On top of that, every agent tells me that they will have to cancel the return flights and re-book - but at the higher post-1 Apr rates, which leaves me insufficient miles and higher tax. In the end, I pointed out to the last agent that this breached the terms of the ticket conditions (change fee only, no penalty on taxes or miles) and he backed down.

Of course, by the time I reach AMS and even have the opportunity to get to a ticket office I will have started my outbound journey and so will no longer be able to change routing or airline under the Classic Award terms.

I didn't really need another excuse to leave KLM, but they simply keep putting more and more in front of me ...