Rude cashier and threats

I went to boxer to buy a few things and than requested a cashback .The cashier who was serving me was down right rude to me.He gave me back the card and I asked about the cashback and he said he wouldn't have given me my card back if he had any cash. He than proceeded with ringing up my things and started serving another customer without even offering me a plastic packet. I had to go to another cashier who sold me a plastic pocket and on my way out of the store I said to him "that is no way to talk to a customer ,you are very rude please do better next time" and he threatened me and said I better make sure that we don't ever meet on the street ...I asked if he was threatening me and I went to the manager's office. The manager tried resolving the issue but the guy was rude and condescending to me even in front of the manager. I was so furious I stormed out of the store. I am so ****ed right now I am even contemplating going to the police station to open a charge of ************!!!!