Today, I went to center again and made a report regarding the quality of phone they provided to customer and request to switch my phone model from 3GS to 4G. It doesn't not worked. I'm not allowed to switch. WTF !! i ever told them i have no trust and fed up towards their phone. But, thanks god because I was served by an Indian guy with a handsome look. This made me talked with a soft voice. HAHAHA. But, have to admit, the services he provided is better than the previous one. He explained and solved the problems for me. I talked to him for almost one hour and he promised to serve me on my next visit. Lol ^^
Finally, my phone "RECOVERED"