Need help Creating the ER Diagram for the following system. THANKS!!!

The system is for a typical Car Renting Company. The main function is to rent cars to its customers. The company keeps a number of offices in a variety of cities and locations within each city. Each location maintains a number of cars. The car types include: Economy, Compact, Midsize, Standard, Full-size, Premium, Luxury, SUV, and Van. Each type has different features, different daily, weekly and hourly rates, and different per-kilometer-rates (charged for kilometers driven above the limit), and different weekly, daily and hourly insurance coverage. A customer can reserve a vehicle for specific days, can rent a vehicle, or return the vehicle that she/he has rented. To make a reservation, a customer provides the location, the type of the vehicle and the day and time for which she/he would like to pick up and return the vehicle. If there is a vehicle of the requested type available in that location, the system shows an estimation of the cost. The customer can then proceed and make a reservation or cancel it. To make a reservation, the customer provides her/his name and phone number, and the system prints a confirmation number. To cancel a reservation, a customer must provide either the confirmation number or their phone number and the dates. To rent a vehicle, a customer provides the same information as that required for a reservation. If a customer has already made a reservation, she/he needs only to provide the confirmation number or their phone number. The system gets the rest of the information from the reservation record. To complete the rent agreement, a customer has to provide their driver's license number and credit card information consisting of the card number and expiry date. The system only accept MasterCard and Visa. When a customer returns a vehicle the clerk enters the date, the time, the odometer reading and whether the gas tank is full. The system calculates the charges by applying weekly rates to whole weeks, daily rate to remaining days and hourly rate to additional hours. It calculates the insurance cost in a similar manner taking into account the insurance rates for the vehicle. To pay their bill, customers can use their credit card or cash. A system administrator can access all the menus and can manage cars and customers and sets all the rates and costs for cars. When a user starts the system, the system asks the user for an id and a password. Then the system starts up the appropriate menu for the current type of user