Forensic Software recovery

I am looking for a person who specializes in Forensic data recovery. I need to recover data files from a Hardware RAID drive that was managed under Linux (Buffalo LinkStation Duo RAID) The situation: There were two RAID drives that had been originally formatted from 2 - 2TB drives to 500GB (each drive resulted in 500GB). There was 495GB of data on the RAID drive. On the RAID drive were 4 shared folders. The largest shared folder was 490GB which is in tact and was backed up. The other 3 shared folders were never backed up prior to a new drive partition and and quick drive format. After the 1 shared folder was backed up, the RAID drives were partitioned into a Mirrored 2TB drive. The the drive was quickly formatted for Mac Journal. All of the 490GB of data was then copied back onto the newly partitioned and formatted RAID drive. Upon realizing the mistake, there are critical data files that need to be recovered from the prior existing 3 shared folders (that amount to around 5GB). Questions: Is it possible to recover the erased data after a partition and quick format of a drive, ASSUMING the sectors have not been overwritten on the platter? When writing new data to a drive platter, does the new data overwrite existing erased data on a platter, or does it only write new data to new data sectors of a drive? Understanding the tree of the drive is not available, could the missing 3 shared folders be recovered? after a partition, quick format, and overwriting data? This project is quick a challenge - if you are willing to take it on. As I cannot send the drive to you, you will have to walk me through using a Linux Dell Laptop at the source RAID drive. Please send your opinions if you think this is a lost cause, or if the data still exists and is recoverable. Thank you.