I filled a formal complaint with Amex when I came back from overseas. I received their response last week (> 4 weeks). Their response is:
(a) It's against RewardPay terms and conditions section 18 (and they supplied me with a multipage printout of same)
(b) it's a prohibited Amex transaction and quoted the charge card terms and conditions. (despite me using a credit card)
"use your card to obtain cash from a merchant for a charge recorded as a purchase;.
It would appear to me that RewardPay encourages breaches of its own Terms and Conditions by promoting the payment of Superannuation (or ATO). In fact it appears to be Reward pays main feature that they use in marketing.
From Section 18 - it is very clear tthat neither the ATO or SuperFund is a "supplier of goods and services received in the general course of conducting Your business".
Its no surprise that AMEX would be taking issue with this, and is probably actiively pursuing large transactions paid to Reward Pay. I would say that AMEX has no case to answer, and that your complaint should be directed to Reward Pay.
You must not use RP’s Payment Facility for transactions other than bona fide payments to Your suppliers in relation to goods and services received in the general course of conducting Your business. This means that You must not use RP’s Payment Facility to make payments that do not represent bona fide purchases of goods or services from Your suppliers, e.g., payments to Your own establishments by You, or Your family members, or employees, or any other person contrived for cash flow purposes.