Fix problem and add Feature in my app

I have an app for ios and android and my site is linked with api on my site but we have a problem with the payment process and especially the payment process we use is not from the app store or google store and the payment process used is Tap. For more information about the payment process: Https://[login to view URL] Payment in the application is directly in the sense that the customer wants a service that pays and then takes the service problem here. The customer pays and is deducted from it and the payment process is successful but the request is not sent to the panel at the site. I would like to change the process instead of being direct payment of services is as follows is added button through which the shipping account and then purchase services as is my site. Of course, the application api is available Knowing the process of shipping the account in the site will be via tap also and there are no problem problems appear only by application A professional person is required for IOS and Android to solve the problem whether it is a problem from the programming application or api The files will be sent for freelancer