We're barely getting any hot water in our downstairs shower and almost none in our upstairs shower (directly above). I've taken off the hot water valve and have been trying to snake it with a wire hanger but without any luck. I have no plumbing knowledge and can't afford a plumber. Is there a way to fix this without opening up the wall and installing new pipes, which would be impossible for me? I've tried the wire hanger and vinegar and baking soda with no luck. A year or so ago I was able to fix it with a hanger and the sediment shot out but no such luck this time. Our family is really desperate with this problem. Thanks.

When you have the valve off did you try turn the water back on to see if there is actually plenty of volume, could be you valve is clogged

We're barely getting any hot water in our downstairs shower and almost none in our upstairs shower (directly above).
What kind of pipe, copper or galvanized iron?