Support
One address, and a person on the end of it.
Write to us
Anything about jamwi goes there: something broken, something missing, something the band should be able to play and cannot.
If something is broken
What helps most, in this order: what you did, what you expected, and what happened instead. The chart it happened on is worth more than a description of it, so attach the song if you can. A browser and its version help too, because sound is the part that differs most between them.
Your songs, if something goes wrong
They are in this browser and nowhere else, which is the risk as well as the promise: clearing site data clears them. Exporting is how a song leaves the browser, as MIDI for a DAW or as a printed chart for paper, and it is worth doing for anything you would mind losing.