Poor customer service

Extremely bad service from game store southgate Mall. I bought a Hisense 58" tv, when i get home and plug the unit i notice the unit has a big black mark on the screen when turned on. This unit was bought on the 04/11/2020 and i took the unit to the store the following morning (05/11/2020 )to ask for unit to be exchanged . The floor manager gave me a very bad attitude and tells me i dropped the unit, which i never dropped it. When I aske for the store manager I was told he is in a meeting and i end up leaving without speaking to him. I then try to call the suplier Hisense and i was told to take the unit back to the store for store to do credit application ,but we had an argument with the floor manager and the store manager was no where to be found which led to my problem unresolve.