Asus India — regarding my service experience and the product

Address: Hyderabad, Andhra Pradesh, 500050

Hi team
I have taken asus zefone selfie and once i have upgraded it then the volte was vanished and i have visited the service center at begumpet they were very rude and impolite and the service technicians was manner less with me and they said that there is a hardware problem in my mobile which takes 4 days for time so i asked them to give me a mobile for temporary use but they refused to do so so could you please tell me what should i do for the same i need an appropriate action regarding the issue and
Particularly in begumpet service center which is located on rebook showroom first floor they are giving the product with damage and loss could you please arrange me a new quakity phone without any problem