Ted here from Shopify, thanks for posting your query!
I'm sorry to hear that you are unable to contact our support. Our support is available 24/7 via live chat, phone and email here via our Help Centre, can I ask what occurred when you tried to reach out to us?
To help renew your domain, I've sent you an email privately to help authenticate the account. Please keep an eye out for my email and reply back to me when you can.
If there is anything else I can help you with, please let me know, I'm happy to help!