Small Claims Case

I have sell a vehicle to a teacher which is I bought at Toyota. before they bought and sign an agreement with me I told them that the vehicle is still insured at People's General Insurance issued by Toyota when I purchase the said vehicle. when we get to sign a sales contract agreement the vehicle insurance already expires. now the teacher (buyer) still have a balance of 30,000 which now they insists to pay cause they told me that the car I sell to them doesn't have any insurance. and for what I know is once the acquired vehicle is sold to another person then the owner has the right to cut all that is connected to the previous owner. 2ndly ang reason is the mother who bought and made an agreement with me is not reading a contract. which under the sales contract agreement i made is loaded. umabot kami sa Barangay and i have just requested a notice to file action since we cannot settle things out. so Sir what is your conclusion here?