I had just sent a company my invoice for designing their new logo, and the guy I was working with texted me the very next day.

Client: Hey there. I just wanted to let you know, my boss loves the new logo, and we got your invoice and everything… But my boss wants you to make some changes on the invoice.

Me: Okay…? Did I get the company info wrong?

Client: No, not that. He wants you to change the payment amount.

Me: Absolutely not. We settled on the price before going into this, and everyone approved of the logo design, and I expect to get paid exactly what I have billed you for.

Client: Oh, sorry. You see, my boss was so impressed with your design that he actually wants to pay you more than we agreed.

Me: …what?

Client: So he wanted to know if you could update your invoice for our records? Just double the amount you have listed.

Me: Uh… Okay…?

Client: That isn’t going to be a problem for you, is it?

Me: No! Of course not! Not at all! I’ll get that updated invoice to you right away!