Sheila,  Fron an outsiders point of view of your stated situation,  it doesn't matter if it is,

"just money i advanced for copies" or anything else, the over all concern should be that

as you said, "THEY OWE ME MONEY".  The reason doesn't matter a debt is a debt, and

should be paid.  Hold tough on your cutting them off and start collection to get your money.

My power company won't listen to excuses or reasons, they just want their $$$$.

You should also.