Hi brklyncam,
There are a few things in your post that I need to have clarified:
1) Who gave you the expense account - the independent sales rep company or the main brand?
2) Are you sure that you didn't sign anything for the expense account? Typically, businesses that grant expense accounts will make the person sign a document BEFORE granting the account to check the person's credit and to make sure the person understands what the account is supposed to be used for.
3) Did you contact the company to find out why you were receiving invoices for these items?