OnePlus - One Plus Service Center formatted my phone

Today I switched on my phone, but the starting screen was a bit different. The first screen it showed was select Language, I clicked on power button and the flow moved to next screen. I got scared as I didn't want to delete my personal data. So I visited One Plus Service Centre in Amritsar, hoping to find a solution. I googled alongside, so I guess it was decryption mode screen. As the text in screen was chinese, I showed the lady in the service center. First they suggested that it needs New Software Installation. She selected one option without knowing the exact meaning of that Chinese test. She took my phone to someone inside, when she came back, I saw progress bar visible, that means they clicked some more options with absolutely no reason. Suddenly it clicked me, I used Google Translate on my other phone and translated the setup. I did not clear my system data and cache and exited the system. When the phone restarted, the damage was already done. They formatted my phone and I lost my precious pics of me and my family members. First of all the progressed my setup without even thinking of closing it, then the were suggesting for Software Install, even though it is now working(with no data).

Address- SHOP NO ** GF, NEHRU SHOPPING COMPLEX, Lawrence Road · Near Novelty Sweets & Restaurant, Amritsar, Punjab, India