Mythic Contingency's duration is 1day/level and (not using the Augmented Version) I cast 1+half your tier's companion spells on it.
With Mythic Wish I can duplicate a mythic spell I know.
The description of Contingency says:
You can use only one contingency spell at a time; if a second is cast, the first one (if still active) is dispelled.
But I do not cast another contingency spell, I cast a Limited Wish.