Worst Customer Service

On Wednesday 24 April 2018 my Iphone 7 Plus, which I purchased in September 2017, switched itself off and did not want to start back up. On the 26 April 2018 I took my phone in to the Istore Woodlands to have it repaired. The consultant explained that they might have to send it to their service & repair centers. Since the 26 April no one has called or told me where my phone is, what damage is on the phone or how long it will take. A total of 8 working days & 12 days in total. I have tried every single number for Istore Woodlands and Icore Repair Center. No one picks up the phone. A internationally recognized company that does not provide customer care at all??? This will definitely be my last Iphone.