Well,

If you can't recover the partition then:

1. You are using the wrong tool, try this:

http://www.partition-recovery.com/

or,

2. Your drive is well screwed, so try this:

http://www.roadkil.net/

"Unstoppable copier"............. available in Windows and Linux versions. Just recover what you can and start again with a new drive........... hell they aren't that expensive are they?.............. you can get 1Tb for around $220 (USD)

The first software is pay for, the second one is free.

What I cannot understand is why you don't set up RAID arrays for these customers, or at least sell them the kit and expertise to make backups?

but when you decide to reimage the HDD, the image software keeps rebooting.
Sorry, you lost me there mate............. why would you want to reimage a HDD when you cannot sort out the MBR, MFT and partitions? All you will do is copy the crap that you already know doesn't work?