Tata Nano — Problem in CNG valve

I have a nano cng+petrol vehicle (2015 model). Despite the car having driven 53, 000 kilometres, the CNG valve is currently having issues. Even after travelling more than 20 kilometres, the car will not drive in CNG mode. When I called the local Tata service centre, they informed me that the CNG valve was not working and would cost more than 18000 rupees to replace. This is a huge sum for my nano car