Bad service

I have purchased a cellphone on the 08/12/2017, and I lost the slip, called Game trade route mall where I have purchased the phone and they Lady told me that I have to lodge an inquiry with the head office so that they can give me the slip however it can take a month to get a duplicate slip. Call the head office number ********** 592 I have spoken to the Lady and she advised that it will be difficult to get a slip sooner, however, I have to call ********** 991 and ask for customer complains. I have called the number ********** 991 and I have spoken to HARRY who claims that he is a manager however he was not helpful and not professional, he advised that I have to speak to the Branch manager where I purchased the handset because they cannot help me without a proof of purchase. I now get irate because I have mentioned that I do not know where my slip is, what proof does he need, he told me about the bank statement, I have asked him that I paid using cash , I did not swipe therefore I do not have the proof he wants and he said he cannot help me. Which does not make sense as I have time, date and month I have purchased the handset and they do have records? Very angry customer.