Please read this before you call anyone else!
Ballast replacement?... Really?
A lot of service companies replace entire ballast kits when a fixture isn't working because they may not know how to troubleshoot it or may not care.
Fixtures are made up of many components. A transformer, a capacitor, a starter, a lamp, a lamp socket, a connection block, and the associated wiring.
We've been doing this long enough to know which components usually fail and how to troubleshoot them. Then we replace only the parts that are bad, saving the customer money -sometimes lots of money.
Really, there's usually no need to completely gut a fixture and replace high dollar parts if it's only a bad capacitor.