Bad customer service IPhone India

My IPhone was experiencing issue that my mobile data is not working in India with Indian carriers. Phone I bought from Qatar on 2015 and whenever I tried to use in India when I come for vacation mobile data not working and called I phone customer care because I confirmed that issue is not with carrier but with I phone. They given three call back request from senior technical executive but all three was missed as per them I won’t believe the third missing as I was kept my phone in my hand with full range eagerly waiting for the call. But I didn’t receive any call and I call customer service again and now they saying they need another call back after four working days to study the case.. I totally unsatisfied as I have already given 3 call back for them to study the case. Case: 101015887572. Am going back to Qatar next week so I closed my case unsolved.