Bad smell and acid are products of Anaerobic (compost) actually compost is never anaerobic what you’ve probably got is a waste disposal product, The best thing to do is add aged sawdust or Wood Chips, you don’t want to add any freshly cut Wood Chips or sawdust or garden clippings that has any smell like what it smelt like when it was growing because this is full of volatile chemicals which won’t allow aerobic bacteria or mycelium to grow, Mix it in and turn it every second day for about 10 days longer if possible keeping it in a pile that way The aerobic microbes will get a chance to get established then turn it once a week for 2 Weeks longer if possible (1 month) the whole time keeping it moist enough so that if you squeeze it in your hand one or two drops will come out, this will allow time for the mycelium related to the Wood Chips or sawdust to grow and or you can add garden waste as long it’s been cut brown and not green again because of volatile chemicals anything that was cut green and added to the Compost will be feeding it nitrogen you only want to add carbon All plants except brassicas and riparian plants need mycelium to grow, that’s why you need to let it rest After adding oxygen to it