Utterly disappointed at brand new iPhone 6

<p>Hi there. I bought brand new I phone 6 from cell c outlet Vincent park east London. It was July phone workedperfectly in July and mid August and from mid August it never worked properly. I took this phone 2 or 3 times to that store they told me it needed upgrade of software but their vi fi doesn't work then I had to do upgrade of software myself but still it doesn't work .it doest open face book you tube and it takes very long to open Google etc. It was working fine fir a month . I am tied of this and very angry about all this. Please help</p>