The first time I called a customer, I didn't say anything. I said I would call him again on Monday and ask everyone if they still need to call.

Don't call, send a text message first. If he doesn't help you or doesn't do it well, there is a buffer stage for reading text messages, which is not so embarrassing. If he doesn't make a phone call directly, he won't have any time to buffer his response. This is not good. If he is too direct, he will be uncomfortable and will have a bad influence on what you do. Just send a text message first and ask as a pathfinder.