FAILURE TO DELIVER AS PROMISED

I have booked in my samsungs5 mini in for a screen repair which is free under the warranty of the phone and I have been extremely disappointed in the service that I have received.firstly my phone was supposed to be back in store ready for me to fetch on Saturday as promised by a technician but I received a call on Sunday saying the cell phone number used to register the phone does not match the number given. I have tried to call in to the repair center many times but I was left to deal with extremely rude staff,the manager on duty said that she would not be able to help me even though I have not changed my number over 3 years and said it was my fault. I have never received such poor service in my life