Harbor Freight Tools

I went to the Harbor Freight in Oswego, NY to return an item. It was a breaker bar with 1/2" drive, approximately $11 value. I had purchased the item 4 days earlier. When I purchased the item, I used a debit card, and I asked for the receipt to be placed in the bag; it apparently was not, or got lost.
I am a disabled USAF Veteran, and I am an end-stage renal patient, on dialysis. I left my dialysis appointment on Saturday May 25th, 2019 and got to the Harbor Freight to return the item around 4pm, with my debit card and other identification. This is what occurred:
I was waited on by a clerk named "Willie". I asked for a return or store credit, and I told him that I had the debit card with me that I had made the purchase with.
He informed me that "...you can't return that; we don't do store credits, either...".
I responded by asking for the manager, which made "Willie" very angry, and he replied in a hostile voice "...the manager will tell you the same thing". He said other things that indicated he was getting upset.
I asked for the manager again, and said I didn't want to talk to him anymore, as he was being very rude and starting to get hostile.
This time Willie became very escalatory, bright red in the face, eyes bulging, and said "...what did you say to me?..", and he puffed out his chest and leaned towards me in an aggressive manner.
I asked for the manager a THIRD time, and he finally called the manager while glaring at me in a hostile fashion.
The manager, "David", arrived, and proceeded to help me. He made the return for me very quickly, and he was very polite and professional. As "David" was helping me, "Willie" continued to talk over the manager and try to pick a fight with me. I ignored him and focused on the manager and the return transaction.
During this exchange, the manager. "David", seemed to be intimidated by "Willie", which made the situation very tense. Many customers in line witnessed the hostile behavior of "Willie". I left the store feeling like "Willie" might retaliate against me. I do not want to go in that store ever again.
Please consider providing "Willie" with some proper customer service training, and perhaps counsel him about his inappropriate behavior, and his disrespect to his manager. I want you to prevent "Willie" from being abusive to any more customers.
Thank you for your consideration.
~ Dan [protected]