Sony Ericsson W800i And K750i — service center changing the parts and not efficient and capable

I had purchased W800i from UK and recently i had problem with the voice quality due to speakers issue. the outgoing sound signals was very low all my frends complained that the voice was very feeble and for this issue i had given to the malleshwaram 5 th cross sony erricson service center i told them the issue the charged me RS 586 /- for the repair which i wouldnt have minded if it was functioning properly. Inspite of paying for the services my phone is not working the battery is getting discharged which was working fine before giving to the repair center now battery doesnt hold any charge even i[censored] charge for more than 24 hrs the battery number is not matching and if asked they said there was a typing mistake and the service does not have any warranty.I have lost faith in the product it self.

My another cell K850i is completely dead after i got back from the service center.