Nokia n79
Not working properly after 3 service

I have purchase Nokia Mobile Model N 79 WLAN:0026cc73915, IMEI No356044031175944. My Set is not working properl. I have taken Three times to Nokia Care, RDC Raj Nagar, Ghaziabad (U.P.)201002. But I am notsatisfied above customercare Centre. My Mobile Soft ware disturbed Again. I am very much fadup with Nokia Care Service.