Refusal to refund after wrong product sold

My name is Liberate Matsoso Maqubela on Saturday the 5th March I went to Vodacom chatz connection shop number 8 in festival mall to purchase a battery for my lumia 620 device I was sold a wrong battery with a higher current value, upon noticing that the battery did not meet the specification for my device I went back to the store to give me the correct battery or fefund me the staff refused to give me a refund dwelling on the issue that my devices on and off button was faulty, which didn't have an effect on the device at all when my old battery was inserted in the device it showed that the battery was empty but with the battery the sold me the device would not on the device the said to me perhaps the devices board is faulty and the software needed to be fixed. When I went to the store my device needed only one thing a battery the software didn't need to be repaired at all the on and off button was fixed and at the moment I'm sitting with a device that doesn't have a battery as the store refuses to refund me and further more I don't know if the battery the sold me might have affected my device due to the higher current value and didn't meet the specification for my device. I can be