checkout page problem using eWAY-rapid payment module

[DrByte]

Not familiar with eway but could you post that file and highlight line 131?

Thanks - the logs appear to be in mydomain.com.au/zencart/logs. The latest entry says:

[25-Jun-2014 18:25:58] PHP Warning:  Unexpected character in input:  '\' (ASCII=92) state=1 in /home3/aap/public_html/zencart/includes/modules/payment/eway_rapid.php on line 131
[25-Jun-2014 18:25:58] PHP Parse error:  syntax error, unexpected T_STRING in /home3/aap/public_html/zencart/includes/modules/payment/eway_rapid.php on line 131

line 131 is the one that begins $service = ...

        require_once(realpath(dirname(__FILE__).'/eway_rapid/lib/eWAY/RapidAPI.php'));
        $__username = MODULE_PAYMENT_EWAYRAPID_USERNAME;
        $__password = MODULE_PAYMENT_EWAYRAPID_PASSWORD;
        $__sandbox = ( MODULE_PAYMENT_EWAYRAPID_MODE == 'True' ) ? true : false;

        $eway_params = array();
        if ($__sandbox) $eway_params['sandbox'] = true;
        $service = new eWAY\RapidAPI($__username, $__password, $eway_params);

        // Create AccessCode Request Object
        $request = new eWAY\CreateAccessCodesSharedRequest(); 

Guessing that you're using a PHP version older than 5.3.0 but your module appears to be attempting to use namespaces, which isn't supported prior to PHP 5.3.0.
Guessing also that you could try replacing all references to "eWAY\" with blank (ie: removing them), as a temporary workaround. Hopefully that doesn't introduce any naming clashes.
Other than that, I agree with the others: ask eWay for their support in conjunction with whichever PHP version you're using.