Just curious... but have they just been repairing your original system the whole time, or are you getting a brand new system every time? Are the s/n's the same as the one you send in that you get back?
If that's the case...then I'd contact them again, and explain that it's happened 5 times now, and that you'd like a new-in-the-box system.
If they've all been different ones...then I'd say you have issues at your location. Either power related or heat related. Make sure it's an open area with good ventilation, and maybe even get a UPS that filters the power for your TV/PS4/other media devices.