With Practice Ignition payments, we automatically collect payment on invoices created through Practice Ignition. We do not currently have a refund/suspend payment feature, so this would have to be done via a DD back to the client.
Prevention is the best method though, so here are a few things you can do to educate your client:
Advise Client of New Proposal email template - The first email your client receives to let them know they have a new proposal to accept. Let them know here that if they enter their billing details on the proposal that payments will be billed automatically.
Accept Proposal Confirmation message template - This is the message your client sees on their screen as soon as they accept the proposal. I recommend having some text in here to the effect of: If you entered your billing details in, then payment will be deducted on the X day of the month automatically. When you receive your email there is no need to manually make payment. (This message will automatically also be emailed to them after they accept)
Optional - send them the invoice after it's been paid and reconciled. Some of our clients don't send the invoice until after payment has been received, and the client just receives a 'paid invoice' so there's no confusion about needing to pay it