Htc
No replacements of warranted Item

Dear Sir,

I have purchased mobile of HTC Smart F3188 on dated 24.11.2010. I had problem with headphone. Then I went to the service centre to get it repaired. They assured me to replace that with e new one within a week's time. But I was not provided any type of receipt of that. When i got back to them to get it back after a week, they were asking for the receipt. I have visited them twice and got nothing. Please tell what should I do in this regard.