How aboard some drywall/cavity fixings, there is a small bolt that umbrellas back on it's self as you tighten it (NOT A TOGGLE BOLT) You would need to drill your corroded holes slightly bigger to accept the bolts and use a couple of penny washers to take up the space as the smallest bolt only collapses to 3mm. Alternatively you could again drill out the holes to good metal and plug the hole with some chemical metal and then pilot/self tap into this.
Steve
October 2010