Unhappy customer

Few months back I bought Polar Eyes sunglasses from Dischem at Mall @Carnival, so today I went there to ask them to fix or exchange the pair for me and was told they cannot assist me as I do not have proof of purchase. I was assisted by Sphamandla Gubevu an assistant manager who gave me a head office number which I called and still couldn't assist me saying I could have bought the shade else where, even ask maybe if I can bring a bank statement to show that I bought the sunglasses there and refuse to accept it. Can I please be assisted in regards to this matter. My name is Mbulelo