Reply To: Invoice link to online payment after its been approved?

The submit fine for me, but you have a jquery incompatibility that results in no datepicker appearing. Maybe this error makes the forms javascript unusable in your browser. I think it comes from loading jquery ui from google instead of using the correct way to declare that. And then your theme loads it again in a third different version, but wordpress has jquery included so there’s no need for that.
All these jquery and jquery ui versions don’t work at the same time with each other…