Applesolution - Fake Apple authorized service centre

My Iphone XR screen was damaged i want to change the screen by apple authorized service center i searched online and i got Apple solution authorized service center i called on that number and ask for replace the screen as the iphone was in the warranty period but they said warranty is void so you need to pay us so i paid **** to replace the screen & Back glass but after i received the Mobile its started giving trouble that automatically shutting off and heating of iphone, so i called the same center for the solution they check the mobile and said its working no problem its happen * to * times. then i personally went another service center in sion they find out the problem of motherboard issue. but this issues cames after the replacement of backglass, they were not authorized apple technician they may replace some components from the phone .then i again called the center regarding the same but they refuse to accept their fault.now to repair the motherboard its will cost ***** but no warranty. though my phone was in warranty but they opened and void the warranty.