Pixels ‑ Print On Demand

The worst experience ever! I cancelled the last order, refunded customer & uninstalled their app, yet they keep trying to charge my card and email me hundreds of messages every day for 2 months now. I got over 1000 messages from Pixels with the title "Urgent - Shopify Order on Hold - Invalid Payment Method".
I am stuck. It’s a system glitch that Pixels need to fix. I can’t do anything on my end and support just stopped responding. I had to cancel my card, but I am not sure what to do about the email. I can’t change it because I have business cards printed with that email address. It’s an absolute nightmare!