Your email system needs some work
I flew my repaired drone for the first time today and all went as expected. However, a couple of comments about your email reminders. You sent me a shipping label and then probably 30 minutes later you sent me a reminder that I hadn't shipped my item yet. I'm fast but not that fast. I got the invoice for my repair and within the hour you emailed me to remind me that I haven't paid my invoice yet.
I will always pay for repairs, but don't need to be prodded so quickly to do so.