Why does my bath mixer tap still drip?

[PlumbingQuandry]

I changed both the washers today. They were worn but not terribly so. The bloody thing's still dripping. Is there anything else I can do?

the seating that the washers press against is probably eroded. It's possible to grind them smooth if they are not too bad. I'd suggest consulting an experienced wrinkly local plumber, by personal recommendation (not a website).

you don't need a gasman.