I just bought a trench coat for the winter from Theory. It fits me so nicely. Later on I found out that its not water resistant. The purpose for this trench is not only for the cold weather but also for the raining season too. Is there any kind of permanent water-resistant treatment that I can apply on this cotton trench??? I think this is my only option because it is hard to find a fit like this as I am short and skinny. Burberry appears to be long and a bit big on me.