I am confused

A warranty claim was registered for my Iphone 6 and Vodacom fixed it in a really good time but when I received my phone the screen protector was cracked. They specifically let me sign a Device inspection confirmation paper in which there were no cracks, scratches, chips, peeling, bubbles, dents or physical damage picked up.

One of Vodacom shop Secunda Technicians, told me that they had to open the phone to replace the faulty speaker and that they can not carry responsibility for a cracked screen protector.

Is this to what customer service is moving to? Please help me if I am wrong, but how do you give back a phone that just came from repairs, fixed the one problem but hand it over to the customer with a cracked screen protector. Its like servicing your car and the garage take no liability for grease and oil marks on your steering wheel and seats.