Magento

I can get CBA working but not Simple Pay. It gives this error while being redirected to amazon side:

An error occurred when we tried to process your request.
Rest assured, we’re working to resolve the problem as soon as possible.
Please try your operation later. We apologize for the inconvenience.

I checked file lib\MarketplaceWebService\Client.php, the signature version is 2:

private $config = array {
...
‘SignatureVersion’ => 2,
...
}

Anybody got it working at all?

I prefer simple pay because CBA couldn’t get gift card balance deducted from total (same as google checkout).

I have a working Amazon Simple Pay extension available, if anyone needs it. Supports all features, refunds, automatic invoices, immediate return to your store (skips Amazon status pages).

Works for all Magento versions.