Since we're already nitpicking, "overbilling" (without the hyphen) is probably better. https://www.google.com/search?q="overbilling" https://www.google.com/sea

Since we're already nitpicking, "overbilling" (without the hyphen) is probably better. https://www.google.com/search?q="overbilling" https://www.google.com/search?q="overbilling" vs. https://www.google.com/search?q="over-billing" https://www.google.com/search?q="over-billing"