Asus — Warranty denied by Service center - Illogical reasoning

Address: Kolkata, West Bengal

My Phone details: Asus Zenfone 5 A501CG [IMEI/Serial No:, [protected] / [protected] ] Bought on 5th June, 2015 from Flipkart Problem and warranty: I went to service center today informing them the full scenario and also told that I never use any other charger other than the originals, but the service center personal told that the warranty is not covered on this set as because there is a black burning mark on the charging data cable port and possibly the port of the phone is burnt as well.. I told the person that every other mobile service providers repair that under the warranty, why can't ASUS.!! The person told that ASUS has a policy where he pointed on a paper showing that "TAMPERED" mobiles are not under warranty.. I have never tampered the mobile neither did I break anything nor did I open the mobile, then why the Harassment?? The person told that Tampered means everything including Opening/ burning/ etc... I told him that this is not an intentional burn. Fault might be with the charger or cable as well!!! But he told that there is problem with my electric connection.. My family use 9 mobiles in my home and not a single mobile got damaged other than the ASUS Zenphone 5 then in what scenario the problem is with my electric connection??? The person told me that I have to repair the mobile without any warranty and would cost 1600 to 1700 rupees or more... I paid 1000 in advance and he told he will inform me the rest amount required once the mobile is being repaired... Now my question is that why ASUS is selling warranty whereas their own product can be faulty and they are blaming on others/ electric supply etc...this is not a service but indirect robbery from the customers...for a 8K mobile i have to shell out 1.6k just for repair and that too something internal which is not done by me.. I will surely inform each and everyone not to go for ASUS just because of their poor support and illogical warranty clauses...