RCW 19.230.330(3) says that
Every money transmitter licensee and its authorized delegates shall
refund to the customer all moneys received for transmittal within ten
days of receipt of a written request for a refund unless any of the
(a) The moneys have been transmitted and delivered to the person
designated by the customer prior to receipt of the written request for
(b) Instructions have been given committing an equivalent amount of
money to the person designated by the customer prior to receipt of a
written request for a refund;
(c) The licensee or its authorized delegate has reason to believe that
a crime has occurred, is occurring, or may potentially occur as a
result of transmitting the money as requested by the customer or
refunding the money as requested by the customer; or
(d) The licensee is otherwise barred by law from making a refund.
I expect that the software is not written to guess whether a customer is in Washington state, so it may be necessary to alert them to the subtleties of Washington law. When you formally submit the request for refund, you could point to that provision. They may in turn point to clause (c). This law does not create a private action, so you would have to file a complaint with the AG.