Hi.
Try soaking in bucket, hot water with Greencare everyday soaker(i know coles sell it) (i think its made mostly from washing soda, so if you can find that by itself it might be cheaper). It removes the grease (so all the body oils that leave the smell). I also make a paste and use an old toothbrush to scrub into the armpits (cause thats where the smell and deo stains most) and leave it overnight before washing it the next day.