I'm looking to see if anyone has created an interface that can be embedded into a site that allows customers to either increase or decrease their subscriptions autonomously.

At the moment, each time a customer requests a change, there is a manual process that needs to be applied to the subscriptions, which is error-prone and, depending on the number of requests and the business rules, this is an unnecessary time/cost overhead.  

So if anyone has already been down this path, please contact me as I'd be interested in having a conversation.