Being Supplied Faulty Phones

Dear ,
I bought Apple iPhone Model I6 on 03.07.2015 from Aptronix Hyderabad (Inorbit Mall) my Phone Ringer On Off Switch stop working few days before. when i consulted technician from Apple service center on 02.05.2016 he told me that the phone is internally modified we will not give you service.when i asked him without opening set how it will be happen i have never show this issue anyone except apple service center how it will be done can they prove phone was opened earlier.for the same i have reported the issue at customer care on 02/05/2016 with my case id 1100968784 and my phone is lying in service center.
Now kindly provide me a solution to change my i Phone 6 as this is an faulty part on Apple part which was not expected from star rating company. A frustrated customer to wait on. i would appreciate if the same could be done in a day or two.