Magento Subscription module modification (implement payment processor)

General information for the website: Online shop with different newspaper subscriptions
Description of requirements/features: Requested is the modification of a subscription module ("Subscriptions and recurring payments" version 1.9.1) by aheadWorks. The module supports already authorize.net etc. but we need the implementation of a german payment vendor (payone.de).
The implementation can be done via the PayOne API (documentation in german available) or with the payone module combined (maybe easier).
The payment methods that have to be possible with the module and payone are credit card and debit (Lastschrift). If paypal is also possible and not that much work I would request this too (see: https://www.paypal.com/de/webapps/mpp/business/partnerprofile/payone).
I would suggest a German developer because all documentation is as far as I know only in German available.
I could give you access to a special server to develop and test with a magento installation (v1.7.1), subscription module (see (http://ecommerce.aheadworks.com/magento-extensions/subscriptions-and-recurring-payments.html version 1.9.1!) and payone extension (http://www.magentocommerce.com/magento-connect/payone-payment-extension-3-0.html).
There is also a small adjustment necessary regarding the e-mail variables because if more than 1 article will be bought the e-mail displays all products in one row except every article in one separate row.
Furthermore the compatibility with the actual magento version should be verified because the subscription module has been developed for magento version 1.7.1.
Links: www.payone.de, www.aheadworks.com

Iam searching for a reliable developer that will also receive future modification orders.
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