What can I do with my broken Iphone mic?

I purchased my Iphone 4 while living in Hong Kong. I am now back in the UK and the phone has deveoped a problem where the mic cuts out during calls and the person I'm on the phone to can't hear me.

I took the phone to the apple shop here and the girl told me that she would have given me a replacement but she can't because the phone is slightly different than the UK (european) model of the Iphone 4. She then told me to call apple care and explain to them over the phone.

I called apple care and an american woman said she can't give me support unless I pay £25 but will email me instructions on reseting the phone, I told her reseting won't make a difference as the mic problem is a common one with Iphone 4's and I've read it's a hardware problem. So anyways I reset my phone and nothing changed.

I'm stuck in limbo right now and dunno what to do, does anyone have any suggestions?

I think I'll get a galaxy when my contract is up this year.