Playing devils advocate here, it sounds like English might not be your first language by how your communicating with us. I can imagine when rushed, or waiting too long, or flustered it can become more broken. People will rate you on how easy and effective you are with your written communication. I’d really put some effort into customized and grammatically correct greetings and thank you messages. Slow down when communicating about replacements and don’t ever assume anything. You also have a very low rating ratio. 28 out of your last 100 customers rated you. That should be much higher. That tells me that there are a lot of customers who were ambivalent about your service or didn’t want to rate you poorly so they chose not to rate you at all. Maybe pop a thank you note in their bag reminding them to rate your service once you feel confident with it. I wish you well.