Originally Posted by MfromL

Actually, the agent was right. This was made public last year, but of course, IB does tries to keep it little known so passengers do not abuse the policy. You can read it here using Google Translate. This, however, only applies to IB, not OW airlines nor IAG partners. And, they might charge you a differencial price —under the logic that the one-way ticket is more expensive that a roundtrip.