Help me update my my Delivery IOS and Android app

I hired a team of app developers last march but they did a poor job on delivering a completely functional delivery app. The app was submitted and approved by IOS and Google Android and is currently available for download on their platform. I am looking for someone to work with on an ongoing basis to update and slightly redesign part of the app. The app was coded on the front end in Swift on the IOS Side and Kotlin on the Android Side. The back end was developed in Node.JS. The app is currently hosted by AWS on an EC2 virtual machine Server. The app is currently functional to a certain degree but it needs to be improved in many areas for a better user experience. App is also connected to external systems such as Twillio for OTP and Stripe for payment Processing . I am in possession of the source code for both IOS and Android apps. I am looking for someone to work with on a long term basis. You must familiar with all or most of the systems involved and must be a very experienced swift and Kotlin Programmer. You also have to be fluent in english so that we can effectively communicate verbally and in writing. The name of the App is VanDelivery and can be found both in the Apple and google Play store. There is also a socing app for drivers Called VanDelivery Partner. Please DO NOT Contact me if you did not take a look at the app or are not an experienced swift/Kotlin/Node.JS developer. This is not a project for rookies.