You had an advisory on your mot and you didnt get anything done about them?
That is pretty irresponsible in my eyes, considering it is used on the roads. And is something as serious as the sills.
I bent one of mine slightly the other day, the jack basically may a little goove in it, as said i would probably let a garage make something up for there, as in the long run it will probably be a lot stronger than any others. As it will be of a custom metal.