Integrating Coldfusion and Pay360

Does anyone have any experience with integrating a Coldfusion website with Pay360? Basically our online shop needs to direct the user to a payment screen on Pay360 using the hosted cashier. The documentation is a bit vague but essentially we have to pass an API username and password, and json string to their request URL and they should return a response with a URL to a payment form. Should be straightforward using cfhttp but I get an error:

{“status”:”FAILED”,”reasonCode”:”exception.request.content”,”reasonMessage”:”Invalid request content: Unexpected character (‘/’ (code 47)): maybe a (non-standard) comment? (not recognized as one since Feature ‘ALLOW_COMMENTS’ not enabled for parser)”}

No one at Pay360 seems to be able to help. I’ve also tried using PHP (having only found one example on bronco.co.uk by doing a Google search) but that doesn’t work for me either.

This is my code. If anyone can give any advice (or has a working CF or PHP script that could point me in the right direction) that would be great, thanks!

<cfset variables.username = "xxxxxx">
<cfset variables.password = "xxxxxx">
<cfset stFields = {
  "session": {
    "preAuthCallback": {
      "url": "http://www.example.com/callback/preAuth?status=SUSPEND",
      "format": "REST_XML"
    },
    "returnUrl": {
      "url": "http://www.example.com/transactionResult?MERCHANTREF=761585761585"
    }
  },
  "transaction": {
    "merchantReference": "761585761585",
    "money": {
      "amount": {
        "fixed": 100
      },
    "currency": "GBP"
    }
  },
  "customer": {
    "identity": {
      "merchantCustomerId": "1111111111111"
    },
    "details": {
      "name": "given1 Family1",
      "address": {
        "line1": "matched",
        "line2": "initialCustomer1AddresssLine2",
        "city": "initalCustomer1City",
        "region": "initalCustomer1Region",
        "postcode": "AVS111",
        "countryCode": "GBR"
      },
      "telephone": "0044111111111",
      "emailAddress": "[email protected]",
      "ipAddress": "1.1.1.1",
      "defaultCurrency": "GBP"
    }
  },
  "financialServices": {
    "dateOfBirth": "19870818",
    "surname": "Smith",
    "accountNumber": "123ABC",
    "postCode": "BS20"
  }
}>   

<cfhttp url="https://api.mite.pay360.com/hosted/rest/sessions/5309398/payments" method="post" username="#variables.username#" password="#variables.password#" result="httpResp" timeout="60">
    <cfhttpparam type="header" name="Content-Type" value="application/json" />
    <!--- failed attempt to pass username and password in the body
<cfhttpparam type="formField" name="username" value="#variables.username#">
    <cfhttpparam type="formField" name="password" value="#variables.password#">--->
    <cfhttpparam type="body" value="#serializeJSON(stFields)#">
</cfhttp>

<cfdump var="#httpResp#"/>