Cart2Cart Store Migration App

I think I used this app when first setting up my website. It was some time ago so I don't quite remember but it was showing in the list of apps in my store.
Anyway, after recently clicking on the app in error, I've been bombarded with pushy emails, even though I replied to explain I don't require their services, the hounding emails continue to come.
It's not professional and certainly not a way to retain customers. I most certainly will never use this app in the future because of this terrible practice.