Hi Fran,
Sorry to hear that iontophoresis is not working for you.
20 sessions with 22 milliamps are quite a lot – over what period did you do those 20 sessions? You need to do a session on daily basis till sweat goes away and then reduce the frequency to maintain that.
I have not heard of Ionomat, so cannot comment specifically on that machine. However, unless there is a problem with your specific piece of machine, I do not think that the machine itself is a issue here.
You are doing the right thing – check the water quality. If you get hard water, adding baking soda may help.
However, in the end, iontophoresis is just one of the options – it works for most people I know of, but may not work for all. You may, unfortunately, fall into that category 🙁