Nokia/5130 xpressmusic
Droping network during call

I harish rawat purchased a nokia 5130 xpressmusic on 08mar.2009 from universal cellular point 4-5 chowk kc road nit faridabad. but after two month later a problem create that was network drop during call.i go to shop, he reply to go nokia care. i submitt my phone on 28 may. after two days they returned the phone, that is ok . but problem was not solved. i submitted it 2nd time on 18 june with job sheet no 107433527/090618/37. after some time they call me that phone is ok. but prolem was not solved. i sumitted 3rd time with same job sheet no. but after three time repair my phone is not working .can u tell me what should i do