Car repair by local mechanic not done properly

My car met with water damage because of rain water overflow on 2021 end, and insurance was expired so had to repair it on my pocket expenses. Authorised centre repair cost was very high so had to repair it through local garage in Hyderabad. I have spent around 2.5L for the repair of the car (He didn't told me the amount will be 2.5L) and he handed me the car very late and I followed up with him every week for those 2 years and Finally got it after 2 1/2 Years in 2024 March. He gave me the list and price of all the things he replaced but after 1 1/2 month, My car was stopped suddenly and took it to nearest garage and they inspected and clearly mentioned that the repair was not done at all and they are saying to replace few parts, I spent another 60k for repairs again. New mechanic clearly mentioned that the old repair must have costed only around 50k and not 2.5L. my car is still with new mechanic and they are still inspecting so not sure how much more money I will spend. when asked to the old mechanic about the repairs, he was simply saying he didn't repaired those parts but he mentioned it in his receipt clearly with the amount.( Which is clearly fake) I took loan and paid him 2.5L and he delayed for 2 1/2 years, I am already paying car loan too in parallel. I am thinking of filing an complaint on old mechanic for refund, Please advice on how to proceed