#2144-Credit & Add-on Limit Update Issue

Currently, our developer API does not provide an option to add new credits to existing credits. For example, if a user has 10 remaining message credits and renews their package, there is no system to combine the current balance + new credits. Instead, we are forced to use the reset_monthly_usage method, which resets the balance rather than accumulating it.

Similarly, when reselling AI tokens as an add-on, the API also lacks the ability to increase the module limit by stacking tokens. At present, we must use the assign_module system. However, if the user has already been assigned this add-on, the API returns an error:

{
  "status": "0",
  "message": "User has already access to this addon. You can update it instead."
}

This means there is no direct way to increase the add-on limit when the same module is purchased again. An additional API endpoint or update functionality is required to handle incremental credit and module limit increases without conflict.