To enable AutoPay, you will log into your Tesix MyAccount and select "Payments & Methods" at the very top of your screen.

Once you are on the Payments & Methods screen, you will then select "Use for AutoPay".

Once your request has loaded and states "Enabled", you have now enabled your service for automatic monthly replenishments.

If you wish to 'Disable" AutoPay, simple follow these same steps and select "Enabled". This will revert your  previous selection. 

You are free to enable and disable AutoPay as you wish.