Are the strings always breaking in the same place ? Like it is always the B at the saddle ?

If so you might try (genitally) filing your saddle as if you have a sharp in there it can cause strings to break.

I use graph-tech string saver saddles and they are OK. I'm not sure I believe them when they say they increase sustain however I haven't broken a string in ages (even bending up 3 or 4 half steps on a regular basis !).