For flights within Europe
In case your ticket combines different travel classes, the refund conditions of the coupon you wish to change will apply.
Example: if you travel in Check&Go on your departure flight, and you return in Flex&Fast, the Check&Go refund conditions will apply for your Check&Go coupon and the Flex&Fast refund conditions will apply for your Flex&Fast coupon.
For intercontinental flights
In case your ticket combines different travel classes, the most restrictive conditions will apply.
Example: if you travel in Economy Max Flex for your departure flight and you return in Economy Medium Flex, the Economy Medium Flex conditions will apply to the entire trip.