For this, we would suggest you to get in touch with the nearest authorized service center in your city as they would be able to assist you better. Click on the given link and select your desired city for service centers.
New maruti Omni can't be purchased as the producrion is already been stopped bbut if the dealers have it in their stock then you can buy it. For this, we would suggest you walk into the nearest dealership as they will be the better person to assist you. You can click on the following link to see the details of the nearest dealership and selecting your city accordingly - Car Showrooms
