Here's the Dutch translation. Updates will follow as soon as all features are working and tested.
For those who only use the English (en-GB) language file, see this: In administrator/language/en-GB/en-GB.com_payplans.ini, there were originally a number of language errors from the beginning at Stackideas.
2x Subcription => Subscription
1 x basix => basic
1 x itme => item
1 x sytems => systems