Samsung Champ — microphone faulty

i have samsung champ esn no.16df5cb0 .microphone is faulty so that i cant useing the cell for the last 15 days.i have complained the same at samsung service center at asr.they refused to take the set due to non availability of microphone in stock.so this is the problem of samsung and i am suffring.i have postpaid connection and i am bearing rent for without any calling .till date the part is out of stock in service center. please post the weiver of rent for this period and get the vhandset replaced