Swarovski scope focusing problem?

[mnhunter2]

I have a swarovski 4-12x50 that I have had some trouble getting a clear focus on the field of view and the reticle at the same time, it will focus okay at the low powers but above 8 it will not focus clearly at all. I had the same problem last year and sent it in for repair and was told they couldn't find anything wrong with it. I got it mounted and sighted in and it worked fine for an antelope hunt but in the middle of my deer hunt it wouldn't focus again. Is this a common problem this type of scope? I am wondering what to do with it, having the same problem twice with a high dollar scope is a concern, any ideas?