Form submissions blocked

We are using a form submission at the bottom right corner of this site to an external payment site. Cerber is blocking the data from being passed to the next location. We can’t figure how to whitelist this since it is not similar to a Contact Form 7 implementation.

The URL we are linking to is:
https://epayment.epymtservice.com/epay.jhtml

The form code is:
<form action=”https://epayment.epymtservice.com/epay.jhtml&#8221; method=”post” data-name=”epayment-form”><input type=”hidden” name=”productCode” value=”795IBP796″><input type=”hidden” name=”billerId” value=”IBP”><input type=”hidden” name=”billerGroupId” value=”IBP”><input type=”hidden” name=”disallowLogin” value=”N”><input class=”pay-button” type=”submit” value=”Pay Now”></form>

The page I need help with: [log in to see the link]