make an apps on regular bases

need an app agency or company (not freelancers) to outsource apps in our company.
what we need:
- native android apps
- we provide design and description
- you evaluate it, commit to a budget and delivery time
- we test final master and accept it
- after acceptance we pay via bank transfer (you need to sign a contract with our company)
- we have a queue of 10-20 apps and more coming
- all apps are without backend