Fortunately I get few non-payers, but I do leave feedback for them 'NON PAYER'.

After 6 days of no contact I resend the invoice. Seventh day a message asking if there is a problem as I do not want to have to lodge a Non Payer dispute and explain the ramifications.

Ninth day - lodge dispute.

14 days, still no action, leave feedback

I may possibly be leaving negative feedback for the non payer, but it is POSITIVE for future sellers who have the same problem!