Buy back collection

On the 28 November 2015 morning just before 10am, I went to collect my cellphone Nokia Lumia 530 to be told that they couldn't find my phone. I then went and did what else I needed to do at the mall and after 2hours they still couldn't find my phone. I was then asked by the manager if they can make a copy of my payment invoice for collection, took my number and said they would call me as soon as they found it. Today, I called to hear if they found it and said they did. Arriving at Westgate Mall Cash Crusaders, receiving my found at the buy in centre I was told to inspect the phone, where I found my 4month old phone screen is crack. I addressed it with the consultant, that took it up with the manager and all they said to me is the box of the phone was sealed, but even my new original box is in such bad state that it looks like I have the phone for ages. This is unacceptable as now I as the customer is liable for the damages.