Drying up?

So I am stopping breastfeeding, because no matter how much I change my diet, takeaway the dairy etc my little one is having a hard time with my breast milk. So we have already switched to soy formula. But even though this is my 3rd baby, I am having the hardest time drying my milk up! I am so engorged it ain't funny, I feel like I am on the fast track to mastitis! I have been doing cabbage leaves, pumping a small amount for relief, hot showers and nothing! Does anyone have any other tricks because I am desperate to try anything at this point!