Cup size is an inexact measurement as cup size will vary even with the same manufacturer. The size of the implants are based on a combination of a patient's goals and objectives and her anatomy. In order to provide a natural looking augmentation, the surgeon needs to evaluate many factors including soft tissue coverage, skin laxity, chest wall width, breast imprint width, the shape of the breasts and relative level of constriction to ensure that the breast implants are appropriate for your body.
Cup size is a very nebulous and everyones opinion of cup size is different. I am sure your surgeon was trying to please you, and in the OR felt the result was a B. This is why I have patients try on sizers and make the final choice pre op since it is their opinion of what they want their size to be is what counts the most. Also if you recently had your surgery you may find in a few weeks that you like the extra volume. Many patients feel a little big early, like it better later. Good luck.
Thank you for your question and I am sorry you're feeling frustrated. Unfortunately, it is difficult to guarantee a specific cup size after breast augmentation. A 275 CC implant in one person may make them a B cup while the same implant another patient may make them a D cup. Much depends on your overall chest dimensions and how much breast tissue you had initially. That being said, removing 50 mL of saline from a 275 cc implant will leave it under filled and cause rippling as you suspected. If you truly want to reduce your size by that much, then a new implant would need to be placed. Please discuss your concerns with your surgeon. Best regards.