Web Developer Needed (On Demand)

Need a developer on call. Need someone that I can call on to help with emergencies or monitoring things to make sure the site is functioning correctly. We’ve had issues where the cart page not functioning correctly, discount codes were not working, and usually there are issues when we make small changes to the store.

Looking for a developer who can:
✔️Monitor the Shopify site the site
✔️Need to make changes to script
✔️Offer an on-demand service

Looking for a freelancer tech who can always be on demand for fixes and changes.

❗️Please propose the costs, your response time, and what are the next steps.
❗️Site: grittysoul.myshopify.com