I called A3 to ask if there's upgrade availability on a certain flight departing from ATH, and was told that yes, there are 4 upgrade seats available. I verified I can upgrade this segment using a single voucher even this is the second segment of a connecting flight.

I then made the economy booking online and immediately called in to ask for the upgrade to be applied. The rep almost immediately told me she's sorry, there's "no availability". I explained that an hour or so ago there were 4 seats available for upgrade, and then she changed her explanation to "Yes, there's availability but because the booking has married segments I have to put in a request for another department to change the fare. It's a technical issue." Then she took my phone number and said they'll call me after processing this to tell me "if there is availability" (!!)

Anyone else encountered such supposedly sneaky practices of trying not to honor an upgrade coupon? Any advise how to get the upgrade to be applied?