reapir to cellphone

I took my phone to have it repaired as it does not charge and shut down as I use it. The guy said it can only be a software update or battery but I just bought a new battery.He charged me R180 but when I fetched my phone it still had the same problem, he then suggest I buy a new battery from him for R325, but I told him I do have a new battery. Now he wants to give my phone to his technician to check what isthe problem and then give me a quote on what I have to pay. Why must I pay again? Why didn't he give it to his technician in the first place? This person is only trying to make money out of customers. He refused to give me his name and only said he is the owner of Vodacom Chatz in Brakpan.