Q : Doing multiple loops and multiple if-statements and if-else-statements || RENTAL CAR CALCULATOR PROJECT

my instructions on the project were as followed:

Instructions: Use a sentinel value loop. To create a basic Rental Car Calculator

Ask each user for:

Type of vehicle (May use something other than strings, such as: 1 for an economy, 2 for a sedan, etc.) Days rented Calculate the (For each customer):

Rental cost, Taxes, Total Due. There are three different rental options with separate rates: Economy @ 31.76, sedan @ 40.32, SUV @ 47.56. [Note: only whole day units to be considered (no hourly rates)].

Sales tax is = to 6% on the TOTAL.

Create summary data with:

Number of customers Total money collected. Also, Include IPO, algorithm, and desk check values (design documents).

{WHAT I HAVE GOING AND MY QUESTION(S)}

package tests;

import java.util.InputMismatchException;
import java.util.Scanner;

public class Tester {

public static void main(String []args){
int count=0;
int days;
int cus = 10; 
double DailyFee=0, NontaxTotal, CarType, Total,FullTotal=0;
boolean F1 = false, F2 = false, F3 = false;
Scanner in=new Scanner(System.in);


while (F3 == false) {
    F3 = true;
    System.out.print("Press 1 to enter Rental Calculator or else press 0 to quit\n");
    System.out.println("Please only enter 1 or 0. Also, please only enter number(s) not letter(s)");
    try {
        cus=in.nextInt();
        if (cus == 0 || cus == 1) {
            F3 = true;
        } else {
            F3 = false;
            System.out.println("Number must be either 1 or 0");
        }
    } catch (InputMismatchException ex) {
        F3 = false;
        System.out.println("Invalid entry");
        in.next();
    }
}

    if(cus == 1) { 
        while(F1 == false) {
            F1 = true;
            count++;
            System.out.print("What vehical would you like to rent?\n");
            System.out.println("Enter 1 for an economy car");
            System.out.println("Enter 2 for a sedan car");
            System.out.println("Enter 3 for an SUV");
            // 
            try {
                CarType = in.nextInt();
                if (CarType <= 0 || CarType >= 4) {
                    System.out.print("Number must be 1-3\n");
                    System.out.println("Please enter 1 for an economy car");
                    System.out.println("Enter 2 for a sedan car");
                    System.out.println("Enter 3 for an SUV");

                    F1 = false;
                } else {
                     if (CarType == 1) {
                         F1 = true;
                          DailyFee=31.76;
                } else if(CarType == 2) {
                        F1 = true;
                          DailyFee=40.32;
                } else if(CarType == 3) {
                        F1 = true;
                          DailyFee=47.56;
                }
                while (F2 == false) {
                    F2 = true;
                    try { 
                        System.out.print("Please enter the number of days rented. (Example; 3) : ");
                        days = in.nextInt();
                        if (days <= 0) {
                            System.out.println("Number of days must be more than zero");
                            F2 = false;
                        } else {

                            double x=days;
                            NontaxTotal = (DailyFee * x);
                            Total = (NontaxTotal * 1.06);
                            FullTotal+=Total;
                            F3 = true;

                        }
                    } catch(InputMismatchException ex) {
                        System.out.println("Answer must be a number");
                        F2 = false;
                        in.next();
                        }
                    }
                }
            } catch (InputMismatchException ex) {
                F1 = false;
                System.out.println("Answer must be a number"); 
            }
        }
    }
    in.close();
    System.out.println("Count of customers : " + count);
    System.out.printf("Total of the Day : $ %.2f", FullTotal);

    }
}

{MY QUESTIONS}

1. When a letter is entered to the prompt "Press 1 to enter Rental Calculator or else press 0 to quit" it displays, an error prompt the user then asks for input again. Similarly, when a letter is inputted at the prompt "What vehicle would you like to rent?" the console continues to print lines with no stop? I do not know how to fix this?

2. I want my program to allow multiple inputs. However after one input the console post summary data rather than looping?