Agree with what everyone is saying regarding hassling phone calls about payment. I must have had 10 messages on our voicemail saying that we owe them money. Finally just answered the phone and was told, "Our system shows that the invoice has not been paid." I pulled up the cancelled check and immediately got the response. "Oh, I'm so sorry. I will look into why this does not show as paid..." BEWARE! And keep all records of payment.