I'll arrange for you to be billed.
I remind you that you purchased the boxed version of the product (as it is at the time of purchase) - initially there was no such integration at all. The integration was done exactly as required by the API at the time of its implementation.
We will make changes and update our paid cloud clients - their tariff implies small improvements, etc.
Your vision now is equivalent to the fact that I can take a car bought 4 years ago and come to an official dealer and demand free tuning of my car, because I once bought it from them, they are now obliged to me all my life.
As far as I know, we only owe you the correction of errors on our part. And changes in a third-party service are not our fault.
If they change something on their side, while breaking the current integration work, there will be 2 solutions:
1. We are making changes and updating cloud clients, because their paid plans imply such support.
2. For users of boxed versions - revision (at least get New Post to make 2 api options, or pay for revision instead of you)
If this is a new functionality that someone needs - this is a refinement / improvement depending on the complexity / time / tariff of the client.
We should not have provided for something that was not indicated in the terms of reference or documentation of the service with which the integration is being done.
For that matter, and you claim that we should have done your integration differently - justify this with the terms of reference for integration, as well as the service documentation
https://dev-api.checkbox.in.ua/api/redoc#operation/create_receipt_api_v1_receipt... - where exactly it is indicated about the payment transfer format - at least it is indicated there that the value can take the integer data format - and these are values \u200b\u200bfrom −2 147 483 648 to 2 147 483 647. And without indicating that in the documentation, we consider it logical that incoming payments is a positive amount, and outgoing (returning amount) is a negative amount.