Thank you for your question. Pictures would be helpful to provide a more complete answer. If the left breast implant has dropped more than the right, you may have lost some upper pole fullness in the left breast, and this may cause the left breast to look smaller. If you have saline implants, volume loss form one implant would make that breast smaller, and could produce a mild sagging appearance. If the left breast does sag more than the right, this is likely related to the presence of more skin excess/laxity on the left side. It is conceivable that this was present preoperatively, but not recognized; or perhaps just made more obvious by the presence of breast implants. There may be small differences between the right and the left breast with respect to size, shape, inframammary fold position, nipple position, and skin laxity for example, that may not be obvious to patients preoperatively. Brest implants sometimes accentuate these differences and make them more obvious - perhaps that is what has happened in your case. If the left breast does sag more because there is more skin laxity on that side, and you would like to tighten the skin envelope, then this will require (breast lift) surgery. The cost will depend upon the work involved. I would recommend going back to your plastic surgeon to address your concerns. S/he is familiar with your preoperative shape, your surgery, and can provide the best answers to your questions. Best wishes.