> In the case that we are unable to find a reasonable alternative flight(s) or other means of transportation, due to a disproportionate price difference between the potential alternative transportation and the original price for the unused flights, we may agree with you on our proportional contribution to the costs associated with a mutually agreed upon alternative transportation.

This doesn't sound like a 100% guarantee. Most of the times on the day tickets will be a lot more expensive than advance purchases.