My guess would be they wilted due to being in full sunlight. Calla lillies prefer either East or West sun. Mine are planted on the West side with a fence protecting them from the sun & do very well there. You might want to check this out:
www.essortment.com/all/growingcallal_rncg.htm
Good luck & God Bless.
www.essortment.com/all/growingcallal_rncg.htm
Good luck & God Bless.