I would first check the AZ web site and see if they are still selling tickets for your flight. It is possible your flight may already be cancelled to MXP.

I flagged the AZ issue to my brother, who had tickets from LHR-MXP this summer, and his flight had already been cancelled - and he was never contacted. They told him they would give him a refund tomorrow.

Nevertheless he purchased tickets on BA - at still a good fare. The good fares on other airlines may go away if AZ fails.

AZ could still sell a ticket from LHR-MXP, but with a stopover in AMS (likely KL) at a price 5 times the price before.