K.B.
if you haven't already tried the vinegar, I would try that. If you are reluctant because you think it will give them a bad smell, try apple cider vinegar, red wine vinegar or rice wine vinegar. Of the 3, the apple cider vinegar should have the least vinegar-like aroma. If that doesn't work, try using 1 1/2 times the regular detergent amount and add a fabric softener (bounce is a great one). But do this after the towels have been thoroughly dried... Good Luck!!!