Standard Chartered Bank — UPI Fraud_ Bank Didn't do anything

I had faced a very bad experience and service with Standard Chartered Bank.
My Account No: [protected]
Contact No: [protected]
I placed a complaint about UPI fraud on 11th April 2021 via customer care. After few days, When I called the bank and asked about the status, they told me we haven't registered your complaint. (Pathetic)
Again I told him to file the complaint and take some action ASAP. but this bank didn't take any action. According to RBI, the bank has to close the case in 45 days.
but this bank starts the investigation after 65 days i.e. 16th June. (Note the date- 11th April to 16th June) and asked me to mailed the FIR copy. I did.
After 2 days, They deposited the same amount on my account, Which is called the Blocked amount, Initially, I didn't know about this. So I thought, I got the money. But after few days when I tried to use this money. I was not able to do the transaction. I called the bank, Again he told me we are investigating.
July has gone - No call from the bank
August (Multiple times): When I called him and asked the status, they told me we are investigating.
September: Again I followed up, After 5-6 calls in September, They mailed me we are done and you are liable for this.
No one call me and informed the same. Now, What is this? If this is not on your Investigation part then why did you make me wait for more than 5 months?
If I am saying that this transaction is fraud and filing a complaint within 30 min after the transaction, why you didn't take any action?
Why did you fail to complete the investigation in 45 days?