How do I set up an auto responder e mail when payment is not complete

I assume you are talking about this form: https://www.jotform.com/72851361830859

If you want to send a reminder only to the users who do not complete the payment, It is not possible to send an autoresponder email only to these users. Because, the autoresponder email is sent to the email address entered to selected email field. There is no feature to check if the payment is completed or not.

On the other hand, you can enable "Pending Payment Email" option on your payment setting to receive email for the incomplete payments. 

After that, you can send a reminder manually to your users who do not complete payment according to incomplete notifications. I hope, this helps you. If you need any further assistance by our side, please do not hesitate to contact us. 

Thank you for your prompt response

I will give the 'Pending Payment' e mail a go

Good News. This feature is available now. You can check the further details on the following user guide:

https://www.jotform.com/help/541-How-to-Set-Reminder-Emails-for-Your-Forms

However, this feature does not check if the recipient fills the form or not. If the recipient fills your form and if you do not want that recipient to receive reminder email, you need to delete that recipient from the setting. 

Feel free to let us know if you have further details.