I have tried every thing to stop our mixer tap dripping. I have re seated it , put one of those kit things in that re news the tap tops and has a new seat for the washer and nothing works any ideas.
Chech the seat where the washer contacts the body of the Mixer tap. You will probably find that it is pitted. You can get a seat cutter in B&Q which will cut it back to a clean surface. The good tool costs about £12. the cheaper one which uses emery discs is not as effective. Alternatively, the mixer valve casting may be porous in which case, dump it!