Complaint about Sheet street poor service

I bought an alarm clock at Sheet Street at Majuba mall in Newcastle and immediately after buying it I noticed it had a Crack. The lady who was assisting me told me they are cashing up but I can go to another Sheet Street the following day for an exchange since that was the last alarm clock they had. She called a manager in Village walk in Newcastle to check of they had the same clock and they said they have it I can come. When I got there they told me they don't take rejects from another shop I must go back to where I bought the clock and I explained to them that I can't go back because of the distance a lnd they said they can't do anything about it. They said have a big mouth and they can also deny that I bought the broken clock from them. They asked me why did I buy a broken clock,why didn't I leave it. I was so disappointed with their service to a point I left my clock at the shop. I tried calling Sheet street head office and the lady I spoke with said there'll contact me but did not get any assistance till today.