Sony Vaio faulty laptop

I bought sony vaio laptop two years back.The problem started the day i bought it the processor was very slow .it took lot of time to get started, thinking that it might be a temporary thing,i ignored it but later i realised that something is seriously wrong with it.I called the service center and they assured my husband that they will take care of it.We also wrote some mails to the company . Later they took the laptop to there service center and said they have fixed the problem.
,but their was no change in the performance of my laptop,again my laptop was been sent to the service center and was returned saying we have done what we can this time the condition of my laptop was much more worse than what it was earlier.I was completely disappointed by sony vaio company.Till today i am dealing with the same kind of problem ,it seems there only motto of the company is to sell there product.After sales services of sony vaio is totally unacceptable. I am writing this mail thinking that it might solve my problem maybe to some extent.pl do the needful.