Cleaning resin case of Pink Baby G watch (by 2 users)

I have 2 baby g : 1pink and 1 lt. blue. Both looked very clear and attractive as brand new. I appreciate the fact that besides the different functions, it is also water resistant. It's just too bad that in Less than 6 month old, it looks disgusting, it looks dirty inside the plastic and black along the edges of the bands. I've tried taking one watch apart to brush with soap under and it came out clean,but can't clean inside the shock absorber and I lost one of the very small white button through the process.