No accountability

I gave me phone in to repair the screen, the phone I have been given back is a new one and all my contacts etc appear to be missing. I have left a message on Hello Peter before but the social media specialist does not take my calls, reply to my messages or reply to my mails. My gut tells me the repair place has lost my phone but no one at Cell C wants to take accountability or tell me whats going on. Now I have a new phone I am scared to open ffs