If the system is worse after a clean install, then something is wrong with the hardware. If it is still under warranty, sending it back with instructions to restore everything to how it was originally, since that's what you want, is probably a good idea. Plus, I have no idea how to help you with screens that are non-English.
I had a feeling you were going to say that (due to the way the drive was wiped when you got it back at the start of the thread). Have you checked to see if MSI has RMA service available in your area? It might take longer, but you have a much better chance of getting a real fix if they can accommodate you.
Yes, you should be going through MSI, the MANUFACTURER, not some other company, unless MSI tells you otherwise or unless it's no longer under manufacturer warranty. Even the fact that you sent it to another place for service, which is pretty weird to begin with, could be a problem with the warranty if it's not someplace MSI told you to send it to or take it.
The only exception to that would be if the place you bought it from (store) had it's own extended warranty on it and the warranty through the manufacturer was expired. Otherwise, it should always go through MSI.
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OK, great. Then that sounds like your group! As far as the problem, you pretty much tould us - your laptop is much laggier than it was before they replaced the hard drive. Ask them to take a look at that.