Redirecting sliding snow

I had a metal roof put on my home last year. The contractor anticipated the need for some devices to redirect snow that slides off the roof toward the back of the house in order to prevent it from dumping on my back porch. Unfortunately, the 3 pieces that were installed for this purpose are not at all effective and I often find a pile of snow covering the porch and steps making opening the back door difficult-to-impossible and the steps quite hazardous. I have been in touch with the contractor whose staff have been very slow to respond and only slightly helpful. So that I am prepared to work with them on a more well-informed basis, I would like to have your advice on what might be the most effective ways to address this problem which has recently become more acute due to a wrist fracture which will make removing the snow much more challenging for me this winter. I appreciate your assistance and the opportunity to get your perspectives.

A picture is also worth a thousand words in this case. There are tons of different snow retention systems out there and which system is right for your home depends on application and aesthetic preferences.