This same exact thing happened to me. I've had my Wii from the start, and I pretty much lost everything. From Mario Kart, to SSBB, Need For Speed, AC, ect. Too many Wii games to list. Also all my VC saved data's where gone.
The sad part was, that I included a letter in the package I sent to them with a SD card asking them that if a wipe had to be done, to PLEASE, back up my game files as I have countless hours of game data.
My Wii is returned 2 weeks later, and everything is gone, and my SD card is returned to my still empty. They didn't even bother opening it. No proof of attempting to save my data files.
Still pissed about it to this day.