How can I stop shutterfly from sending me emails?

I keep getting notifications for events from a shutterfly user because my professional email is on her list. She has her site on private and there’s no way for me to contact her. I have no idea who this person is nor is there any way that she knows me. I have never used or even heard of shutterfly. Others have had the same issue and said that the only way to stop this was to contact their customer service. It was absurd enough that I had to listen to elevator music for help with a site that I didn’t sign up for, but I was given two options that did not guarantee a definite solution. One was to simply flag the email so that it will go to my spam folder, but I don’t want them to have my professional email at all. The second was that she sent my email and full name to her supervisor but because they get so many calls, it’s not guaranteed that they’ll ever get to me. How do they not have a faster more definite solution to this? I was on the line with their customer service for 20 minutes.

I asked, “So there’s only a certain success rate for my problem through this call. If I keep calling, will my chance of getting it solved increase?” She responded with a yes.

Is there a more efficient way to getting them to stop sending me emails?