That is exactly what you need to do. The places you've taken the car for help are only taking your money. Calm down and take things one step at a time (obviously the car is not going anywhere at the moment).

How deep was the car in the flood water? How long ago was it flooded? First you should put a dehumidifier in the car and get it thoroughly dried out. Then make sure the battery is fully charged (as per initial advice from James1549). Get an OBD2 trouble code reader and write down the specific trouble codes. Give us that information we can proceed to offer some assistance.