Staples the Office Superstore

Being a repeat customer, who shops for home office as well as a large, busy workplace (with commercial account), I expect only respect and good customer service. I had experienced a moderate level of «okay» customer service until this week when I tried to return one item without a receipt. The older woman at the register treated me as if she were suspicious of my transaction, refused the refund (all I wanted was to exchange for the correct item), lied about the return policy and spoke to me as if I were a criminal in front of other customers and employees.
I wrote to the corporate CS department and received a decent (canned) apology.
Returning to the store for purchases is a distinct NO for me. I will order primarily online in the future.