Quote > Invoice > changed due date, still billing

[Greenix]

HI All-

I created a quote, turned it into an invoice then sent the bill. No problem. I had to change the due date in which I did but the customer is still getting invoice reminders from the old due date - and getting a little peeved I might add.

 

Is this a bug or did I miss a step.

 

Thanks for your help-

M