Need some pictures. How much of the main is back winded percentage wise? If it gets to the 50% 'line', move the jib car back, sheet on the main, and drop the traveler a bit. This is after you've shortened the forestay, have applied max backstay and outhaul. This should be in moderate to heavy air. How far away is the leech and the foot of the genoa from the spreader tip and chainplate respectively?
If it's happening in light air, then either something is definitely wrong trim wise, or the sail is blown out. It's better to have a flatter main and a fuller headsail instead of the other way around.
Merit 25 # 764 "Audrey"