Implants bottomed out twice - why?

Sorry to hear about your misfortune but there is a solution.  I typically use permanent stitches to re create the fold and if I am doing revision surgery I will set the fold with an ADM (acellular dermal matrix).  Perhaps seeing a second opinion will be helpful.

Thank you for your question. Unfortunately without photos and limited information, no specific answer can be given. The "why?" could be a combination of your tissue inelasticity and technical factors based on your surgeon's experience with tissue matrix placement. You said you had "mesh" put in. Is this like Seri or Vicryl mesh? Based on these, and photos, one can give you more specific answers.

Breast implants can migrate in position soon or even years after surgery. They tend to move down and out. A combination of your soft tissue qualities, chest anatomy and the size of the breast implants play a role along with gravity and time. Placing smaller implants and some type of support such as mesh or acellular dermal implants is a common solution. Consider a second opinion and hopefully you will get a longer lasting result the next time.