My old dusty xbox 360 elite black need to be revived.

I have 2 issues with my ebox now :

1)120gb hdd wont detect so I am running games save files off a flash thumb drive
2) I keep getting error when playing games half way,.. DVD cant read error

I need :
1) reliable honest shop to fix the dvd rom lens or drive (i have changed it once f0r 200 bucks, didnt last me a year)
2) revive or format my 120gb hdd, so i dont have to buy a new one

All advice and info sharing much appreciated, thank you in advance.

Owh,. 1 last question,.. how can i tell if my Xbox is using a Samsung/Hitachi/BenQ Dvd rom??
Planning of buying from US or Ebay.