Dell — Poor Product & Servicing

I am a management student and to make my life easier on the campus, had to purchase a laptop.We placed a bulk order for around 150 DELL Latitudes from our campus.Till now 114 laptops have had a problem with the motherboard.Proper servicing could have mitigated this to an extent.But it is equally poor.The chronological order of the problem is as follows:
1.You get vertical lines on your LCD.You call up the Dell call centre and tell them the problem.They diagnose it and say the problem is with the LCD screen and give a time of 2 days.
2.After 2-3 days the engineer visits your place and re-dianoses the problem and says the problem is with the motherboard.(I dont know why this has happened with almost all the 114 lappys).
3.You place an order for the motherboad and you are told it would take another 20 days as the part has to be imported from malaysia/singapore.You have no other option.You got to wait.
4.After 20 days you get your motherboard, which may/maynot work.At present my motherboard is not working and i have placed an order for another motherboard.I am waiting for another 20 days(Total 40 days).
I dont understand why it takes 20 days to get a motherboard when all the laptops have this problem.Why can't Dell expedite its suply chain in the India.WHy can't they have an inventory of spares?WHy should the customer wait for so long?

Cycle time of any operation is a function of the responsibility.You call up a fire-squad and say your neighbourhood is on fire.He would rush becoz he knows his responsibility.That is not happening with Dell.