someone did work for me a few months ago. I emailed them asking for an invoice so I can pay them. They said "OK I will send one soon" but they never sent it, its been over 4 months. I have 2 choices: 1) do nothing. They didn't care enough to send the invoice. That's their problem. If I pick this option, I will be rich. 2) remind them to send invoice. Then pay. If I pick this option, I will be poor. Which one should I pick?