Very bad customer service

I came with my car to buy a car battery on the 16/05/2024 at 15.34pm they took my old battery and gave discount of R300, the battery cost of R2095.00, went home parked the car, in the morning I started the car it doesn't start it's displaying low battery. Took out the battery from the other car putted in the my car the car was starting. I went back to the shop immediately to return the battery, they told me that they don't have other battery of the size I'm looking for, they will return the faulty battery to their supplier, I said it's OK in the meantime give back my old battery so that I can run my car because I don't have any other battery, they refuse to give the old battery. They insist on saying I must wait for their supplies to bring back the new battery. Today it's day 7 no communication from them, they have my old battery they have my money. Everytime I go there they tell me that the manager is not there. I'm so angry about their treatment towards me.