After three hours of emailing with a customer I can confirm that programmers are the worst customers.
Customer: We've found a bug in the system... <details>
Me: Thank you for letting us know, a ticket has been created and the issue is most likely to be fixed in the next release.
Customer: Please grant me UPDATE privileges in the live(!) database so I can fix it myself
Me: I cannot allow that. You have to use the client software for maintaining your data.
Customer: No, I don't want to spend my day clicking. I want to write queries.

We didn't reply to the last one yet...
If we give him access, then I would charge them at least 3x for fixing issues caused by him.