While it sounds like someone at CW needs an @ss whippin for being a lying ignorant cheat, but there's always 3 sides to a story and info is missing from this one.
First, to help determine what might be wrong with the generator, tell us what happened to make you think it ran out of oil and the symptoms. Also total hours on the gen, last time it was checked or filled with oil and how many hours since your attempted oil change at CW.
Next answer whether you filled it and tried to start it? Is it totally seized? Turns over but won't fire? Turns over too fast like no compression? What does the spark plug look like.
There's a half dozen easy, free things you can do to figure out what's wrong with it before spending more money.
The starter needing "replaced" may be related to what you think is seized. My advice is find a small engine mechanic and get a real diagnosis since you're unable to discern what's wrong yourself. CW may be correct or they may be fleecing you.