5th replacement iPhone 4

I have have my iPhone 4 replaced by Apple for the 5th time. All for different issues in less that 1 year.

1) proximity sensor bad.

2) touch screen had developed deadspot, would repeat type of single letter infinitely.

3) bad microphone.

4) bad simm

5) speaker died (at Apple Store)

The iphone4 (number 5) a few days old has already developed microphone issue. After a few minutes on call with 5 full Bars, my collogues tell me i am breaking up and or they can not here me. I am sitting in my office with an AT&T 3G Micro Cell about 6 feet away. The micocell is connect to a 20MBPS

fibre optic cable ISP. We have tested the Microcell by using my wife's little Sony Eriksson cell phone as a control, her phone works flawlessly.

that point is not necessary due to the fact that when I am on the road with high signal 3-5 bars 3G signal form different sources the same issue still occurs.

the microphone breaks up and then dies.

I purchased the original iPhone4 on 06/28/2010 from AT&T store. I have iPhone 3G before it worked flawlessly

I have 2 year warranty but it does not cover my time wasted.

I was told at Apple store that I have just had bad luck with this phone ,

Getting 5 defective iPhones is more than bad luck. Its bad business.

Who do I contact now? This has to be address.