Develop payment gateway with existing working API

We need a Payment Gateway Developer specialist with experience setting up payment gateways for API's.

The current working API (selling English premiership football tickets), sends ticket information selected by the user, we need this information connected with a payment gateway (ideally WorldPay, but would consider others), once a transaction is completed, a success notification needs to be sent back to the API so the ticket can be confirmed/booked.

We’ve built the front-end using Javascript to poll a third party REST API for football event ticket information and availability; The user can select an event by team or from table of all events, and further select ticket types from each event to purchase. The user is then presented with a modal where they can select number of tickets and a buy now button.

We need to send the user to a payment gateway to process their payment, then on successfully taking their payment, return to our app with the transaction data to make one further call to the third party API (using the transaction data from the payment gateway) to process the tickets and remove those tickets from sale.

Upon success return data from the third party API, the user then needs to be sent to a thank you page.

If the transaction is unsuccessful the user should be returned to the app.

We’ve attempted to use WorldPay but it doesn’t appear possible to send the transaction data (full amount paid, transaction ID, quantity etc) back to the app to process make the final call to the third party API to complete the ticket sale.

We need someone who has experience setting up a payment gateway with a notable merchant and able to handle payment side of the app and sending of data back to our system to process the final API.