Employer refusing to pay full salary after resignation?

I resigned from my job in Noida a month ago, fulfilling my notice period as required. However, my former employer is now refusing to pay me the full salary for my last working month, claiming budget cuts as the issue. I’m left with unpaid bills and this delay is affecting my financial situation badly. I’ve tried contacting HR and even emailed my manager but there hasn’t been any response. What steps can I take to ensure I receive my due salary?