I suddenly started getting ‘403 Forbidden’ errors on my map. I take this to mean I have been banned, I assume for violating the ToS in some way. Is there some way I can go about fixing the violations and requesting to be unbanned?
The only likely violation for the tiles themselves is making an excessive number of requests. I would think the first thing to do would be to look into rendering the tiles on your own systems.
This page may help, particularly the link for System Administrators: http://wiki.openstreetmap.org/wiki/Tile_usage_policy
If you are accessing the vector map, see: http://wiki.openstreetmap.org/wiki/Developer_FAQ#Using_OSM_map_tiles