Review They sell products that are not good and refused to change it or refund money

Their customer service is very bad. I went to the store to buy a battery for my glucometer. After buying I told them to test the battery for me and gave them my machine but they said I should test it my self. So I did and found out it wasn't working. So I told them it's not working and they said it's from my machine. I told that my own battery which I had with me was working and I just wanted to buy extra just in case. They tried it and saw that mine was working. So I asked them to change it but they refused. That since I had opened it that they will not Collect it back. I told them that I can't take a battery that isn't working. The manager accused me of swapping the battery to my old one... It was so embarassing. How can come all the way from my house to GRA Enugu just to swap battery to cheat them. I asked them to check the battery with their own machine since they were insisting that the fault was from my machine and they saw that it wasn't working. They said since I had opened it that they wont change it for me. Well after every thing they changed it but the bad thing that scared me was the manager said they should stop checking for customers if the product is good or not which is very bad. That means that someone can buy a medication there and if they person finds out that the drug is expired, they wont refund or change the medication. So people should be very careful. I just wished I remembered to video it.