I had a similar problem with my 94 SuperSport - bubbles and powdering alloy etc.
Took it to a respected local bodyshop this summer and had the car repainted at the holes treated, refilled and resprayed - looked lovely. This was in August 2013.
Putting the car to bed for winter at the end of October and what do I see, bubbles again in the same place - aaahhhhh!!! Spoke to bodyshop who were very good and said just bring it back in, in the Spring and we'll sort it. This I will do, but I wonder how long it will last.
My car leads a fairly cosseted life - in as much that it isn't driven in the rain and I like to keep it clean & polished.
I suspect that panel replacement is the only real way of fixing this issue, but I'm not going down the expense and hassle of that.