Не е решена Trade Commissions

string sity = Console.ReadLine();
double sales = double.Parse(Console.ReadLine());

double comision = 0;
if (sity == "Sofia")
{
    if (sales <= 0 && <= 500)
    {
        comision = sales * 0.05;
    }
    else if (sales > 500 && <= 1000)
    {
        comision = sales * 0.07;
    }
    else if (sales > 1000 && <= 10000)
    {
        comision = sales * 0.08;
    }
    else if (sales > 10000)
    {
        comision = sales * 0.12;
    }
    else
    {
        Console.WriteLine("error");
    }
}

else if (sity == "Varna")
{
    if (sales <= 0 && <= 500)
    {
        comision = sales * 0.045;
    }
    else if (sales > 500 && <= 1000)
    {
        comision = sales * 0.075;
    }
    else if (sales > 1000 && <= 10000)
    {
        comision = sales * 0.1;
    }
    else if (sales > 10000)
    {
        comision = sales * 0.13;
    }
    else
    {
        Console.WriteLine("error");
        }
}
else if (sity == "Plovdiv")
{
    if (sales <= 0 && <= 500)
    {
        comision = sales * 0.055;
    }
    else if (sales > 500 && <= 1000)
    {
        comision = sales * 0.08;
    }
    else if (sales > 1000 && <= 10000)
    {
        comision = sales * 0.12;
    }
    else if (sales > 10000)
    {
        comision = sales * 1.45;
    }
    else
    {
        Console.WriteLine("error");
    }
}
else
{
    Console.WriteLine("error");
}
Console.WriteLine($"{comision:f2}");