虚心请教：这段话怎么翻译比较专业？谢谢!

想本坛的高手们请教，下面这段话怎么翻译比较专业？
谢谢！

"If A resells it to third parties he hereby assigns the entire resulting payment claim to B. In the event the parties agree on a current account, the respective balance amounts shall be assigned. However, A shall be entitled to collect such payment claim on behalf of B until B revokes such right or until payments by A are discontinued. A is only authorized to make assignment of these claims – even only for the purpose of collection by way of factoring – with the express written consent of B."