Have had itchy ears for a long time and though all the usual natural rememdies seemed to work for a few hours, none was long lasting.
Finally, in frustration I added about 10 drops of bleach (sodium hypochlorate) to a 250 ml wine glass of water and swabbed my ears with a cotton bud moistened with the solution. Eureka! At last I have had no itch for days on end.
Because I have no idea if sodium hypochlorate can have side problems I kept the solution weak and did not insert drops of the liquid into my ear. Maybe you should try 5 drops per 250 ml first, and increase drop by drop until you get an effect. Don't be tempted to use a very high strength until we have an opinion on any side effects. By the way... Don't forget that bleach bleaches! Leaks may bleach your favourite black satin pillow or your shirt. I suggest you plug your ears with cotton balls until the remedy dries.