I believe you may have had a simple misunderstanding of Dell's tech support instructions.
Your model Dell boots into Recovery Partition via the F8 key, which is also Windows Advanced Boot Tools. At the top of the list is Repair My Computer
which contains the same System Recovery Options that are on the Windows 7 install DVD or Repair CD. To these Dell adds a Dell Factory Image Restore
choice which runs factory recovery partition.
It is understandable why you mistook "System Restore" from the System Recover Options list for this, without having a tutorial to work from like this one: Restoring Your Computer´s Software to the Factory Settings | Dell
If your store Helpdesk reimaged the HD then hopefully they left intact or replaced the Recovery Partition. The way to know for sure is to burn your Recovery Disks as they are a copy of the Recovery Partition.
Now you know!