Very little you can do if you didn't object when the planning was being granted. I have similar, upstairs windows looking into my kitchen and two main bedrooms in the back (had to buy the dreaded net curtains and I hate them), I objected to the initial planning which was even worse and it was refused but like you I happened to miss the second notice being put up.
I don't think planners give a monkeys about invasion of privacy and to be fair in most town estates all upstairs windows look into somebody's garden/windows as houses are close together, you were lucky that you were not overlooked at all before this. There are I think distances that have to be maintained but they are obviously not that great.
Look into a good big tree that strategically placed will block out the view from the neighbouring window into the kitchen, this was the one I found most irritating, while I know my neighbours were not upstairs gazing over into my kitchen I always felt conscious of it when working in kitchen. I also needed a new garden shed and got one made that was extra high and this has blocked out the overlooking into the kitchen which is great but the gap between my house and next door was a lot smaller than yours so the shed is basically up against my back garden wall which is only about 14 feet from my house.