I think the main point here is that you trusted complete strangers, regardless of whether they were recommended or not, to externally have full access to your computer... brave or stupid time will tell, on which you cannot possibly rely on any recommendation just yet. I'm sure they are "fine" and carry a good reputation. I personally don't sit comfortably with this method of fixing your computer unless you are already acquainted with the company and I think it is bad practise from the company itself for this service to be offered straight off. Why didn't you go to their "shop"/premises with said machine like you did with PC world? Was this suggested to you?