[Resolved]  Lenovo / Desktop — Replace my PC motherboard with Faulty motherboard.

I am having a Lenovo desktop in which a problem occurs in August that it hangs when i am working on it continuously nearly for an hour or so. then i have to restart it again. After discussing a lot with Lenovo customer care department they told me to completely formatted my PC & then reinstall the OS. After doing so on 3rd of Sep 2009 my issue regarding hanging will not resolve. So on 7th Sep. 2009 i register a complaint regarding this problem & got the complaint no. L997006D. On very next day Lenovo service engineer took my PC to Lenovo service center & kept it there for next 5days. & then return me back & told me that they give the indent for the MOTHERBOARD on 13th Sep. 2009. & it will be changed by 16th Sep. 2009 or max. up to 18th Sep 2009. But till 23rd Sep. 2009 i am not able to get any satisfactory answer from Lenovo service center every time i call them. Then decided to visit Lenovo Service center on 23rd Sep. 2009. Then they assured me it will be changed by 24th Sep. 2009 as Lenovo is not able to provide them the new part. Still the part is changed on 25th Sep. 2009. & Motherboard give to me is Old as well as Faulty. So i request Lenovo to return my Motherboard if Lenovo is not able to provide me a new motherboard. today is 1st Oct. 2009 (nearly 25 days) they are not providing me my motherboard or new motherboard. It causes me a lots of problem & i have to go to Cybercafe to do my work.. Please help me...