public class MyService : IMyService
{
    private readonly IInterface1 _interface1;
    private readonly IInterfaces2 _interface2;
    private readonly IInterface3 _interface3;

    public MyService(IInterface1 interface1,IInterface2 interface2,IInterface3 interface3)
    {
        _interface1=interface1;
        _interface2=interface2;
        _interface3=interface3;
    }

    public SomeModel MyMethod1(1Model model)
    {
        //do something here....
    }

    public SomeMode2 MyMethod2(Model2 model)
    {
        //do something here....
    }

    public SomeMode3 MyMethod3(Model3 model)
    {
        //do something here....
    }
}