Failure to give feedback regarding repair

On 28th of March I took my Hisense phone back to Pick n Pay Hyper as i was still under repair guarantee. I kept on calling to hear feedback and the Lady in charge never got back to me, after saying she will and kept telling me about the 21 working day waiting period. Although she was friendly, and I had hope everytime...it all came to nothing. Only at the end of April, when i called repeatedly, she told me Hisense will give me my money back as they don't have the parts (or get the parts anymore) for my particular model. Its 21days later again, and I called on Monday(18 May) and she said she will call back, and never did. I called the Tuesday again and still nothing. I called on Wednesday (20 May) and my number was given to Marius who works at the cellphone department and still no feedback. I am tired of calling!!! I don't know if it is because I am 23 years old that the lady from repairs aren't taking me seriously, but my patience is running out as it is a struggle without a decent phone.