My boyf called, he is far more charming that I am - which may explain the lovely lady's helpfulness

Iberia were terrible (flying to Madrid with them in a week or 2, so hopefully their in-person service is better). Avianca seemed very competent - called LifeMiles to ensure that our super-cheap tickets would be upgradable and then booked, passed us through to the LM people and voila!

We actually couldn't book direct MEX-BOG-MEX direct flights for less than £900 in business class online using anyone's website. But they managed to book us the super-cheap £300 tickets and upgraded them with $900 worth of LM's - works out to around £650 a ticket, which is what we had originally thought it was, until we found the super-odd extra expensive to fly BOG-MEX non-stop return leg weirdness.