How can I fix my wifi ic ship?

i own the Samsung N5100 and i have a problem with the wifi it wont turn on

it act as it is turning on ,but it wont get connected to the local network

and when i reset the factory settings it would only connect for seconds then the problem is back

i got it checked at the local Samsung office and they told me that it would cost around 300 $ because i am out of the guarantee

so all i need is where to find this ship????and how can i repair it?

also i need to know how to increase the sensibility of the s-pen from within the hardware

thanx