If you had agreed an amount for something that was supplied but the supplier never sent an invoice or asked for the money would you remind them?
It's been three months now and the money is in my account waiting to for me to pay. Without an invoice I don't know where to send the money so I would need to contact them but they aren't good at picking up the phone or communicating!
Am I being unreasonable to wait for them to ask me for it?