Data loss compensation... during a remote event a dell tech erased my Seagate backup drive?

There was nothing in the remote assistance that had anything to do with my backup drive. It is not a Dell product. My dell pc is new and has had problems since purchase...June 2013. They were again trying to fix the problem of shut downs and keyboard and mouse freezing problems. The tech did some things without explanation. Then he went to my backup drive and started doing stuff there, I commented on it telling him that it contained important not replaceable data including pictures of my mother who is deceased. He even went so far as to say 'I wish you to ignore it' and continued doing it even over my objections. And he did indeed erase all of my files on my backup drive. Later He did three recovery programs trying to get some of the data back but didn't retrieve it all. Even partitioned the backup drive that wasn't partitioned before and then when I asked him to fix it back the way it was, he didn't do it correctly. Now dell is saying sorry but that is all. They even act like I am at fault for the continued problems because I wouldn't let this idiot continue when he wanted to take my entire system back to factory condition. Anyone know what to do to get compensation for the data loss. They are just making excuses and are not willing to make it right. Should I see a lawyer?