I sent my M550, still under warranty, Acer assistance complaining all the faults I found (solarizations, noise, memories can not be changed, HDR, flicker, etc. etc.), also asking for software updates. On the Acer site, You must register the product and then open a repair request where you specify all the defects, and within 1-2 days you'll receive an acceptance email and another with the packing and sending instructions. Read everything. For me they used 8 days for the return and it's a total free service.