Help me to redesign and make our existing android app work

We have an existing android app and we want to change it to another design. There is already an existing code that can be edited. We will submit the design once we selected the cheapest and fastest freelancer that can create this project. We like it at least in 3-5 days maximum. There is a buyer, seller and driver app. We want it to be all working together with the backend. Let me give you an overview what will you do: 1. We already have an existing buyer, seller and driver app. All of these apps must be connected and running using webservice and same database. 2. The buyer app must be edited in the design and interface. The rest would be the same. Only a part of the buyer will be edited and modified. That part is the home page, cart, favorites and check out. 3. Code is written in Android Studio. There is a webservice connected to our website w/c is written in PHP. This has 13 screens.