Zipper broke, any suggestions on where to send for repair
You could call Prada boutique. They should be able to fix it for you for a small fee.
If you bought it yourself, either from Prada or a department store, and it is within two years of purchase, all repair should be covered by Prada. My department store sends any damaged items back to Prada for me where they are fixed free of charge.
try a really good shoe repair or a place that specializes in handbag repairs
You can also try Margaret's Cleaners/Cleaning in La Jolla, CA. They have a good rep on tPF if you want to send your bag off.
I called Prada NYC about some rub marks on my cera gauffre and they directed me to a repair shop at 84 and Madison called Art Bags. They said they could not handle it themselves (even though I purchased it there).
I think it depends on what type of repair is needed. With defective items (ie plates that fall off, buckles that fall off, etc) the store will take it back and Prada will fix it. The bags are shipped to Prada itself for fixing -- my SA confirmed this, and she said it sometimes takes awhile.
For cleaning and scratches -- that's a different matter.