Unacceptable bill for screen repair

To my utmost disappointment I am leaving a bad review on Samsung. I sent in my S7 Edge for a screen repair as it still falls in my warranty and free screen repair year. I could still use it, only the screen was cracked. Now 3 weeks later they are coming back with a R3000 bill. The best is that I did not even authorise it to being repaired for the R3000. They usually give a quote before fixing if there is a cost involved. The way I feel now is they can shove the phone up their behind and I will go to iPhone as I will receive much better service from them.