T&Cs say :
Companion ticket
- Receive one return companion ticket to bring a companion with you on your journey. First book your Aer Lingus ticketed and operated flights. Then request your companion ticket by emailing your flight details or calling the number on the back of your Concierge card.
Subject to availability, the companion ticket will be issued in the same fare class as the fare paid for by the Concierge member. For example, if the Concierge member buys a business class ticket, the companion will be booked in business class. This is a discounted fare so taxes, fees and charges apply and cannot be used in conjunction with other AerClub benefits eg complimentary upgrades.
Is the last part rigorously applied, or can you upgrade companion ticket ?