No, you can "upgrade in advance" using miles. It is different than the promotional upgrade offer (for cash) at OLCI.
The amount of miles required is fixed and there is a chart for that. For example, to upgrade from Premium Economy fare class A into Business Class on a NYC-CDG route, it is 35,000 miles, but 25,000 miles if from fare class S or 15,000 miles if from W fare class.
To answer
natcho , FB uses a hybrid "dynamic/fixed amount chart" for its awards:
- as long as there is a cash ticket for sale, you can get it with miles (hence sometimes the absurdly high amount of miles like 800k miles on a CDJ-JFK in J).
- for the lowest redemption values (50,000 miles in J for a CDJ-JFK), you still need to tap into the "O" fare class.
For upgrades in advance using miles, you can tap only into the O fare class (the lowest redemption value) – same as an outright award purchase into the lowest redemption award.
If you are Platinum, you can upgrade in advance by tapping additionally into the Z fare class.
So the agent was correct. You see an award ticket in Business Class for sale at 200,000 miles on your JNB-CDG because, by virtue of dynamic pricing, it means that there must be a cash/revenue ticket in fare class Z or I. If there was an O available (the lowest), it would be priced at around 70,000 miles (I don't know the JNB-CDG route very well so I am throwing out this number randomly). If the O was available (or Z if you are Platinum), then, as booked in PE fare class A, you would need only around 35,000–45,000 miles to upgrade.