If that fails Novichok is the go, just keep the dose down to less than 1.9 to 3 mg/m3.i prefer petrol. 150ml soak in plastic fermenter with 100ml chlorine crystals, then get a friend to drop a match in it. guaranteed to get rid of bacteria that might do bad things to your brew, along with neighbours, nearby birds nests and the occasional postie.
then gently sponge black bits back to shiny plastic, patch any holes in the fermenter with sterilised bandage webbing and seal with bicycle patches.
you'll never complain about yeast infections again.