Olx India — I have been frauded INR 3500

Dear Sir/Madam,
We all know that we are not supposed to share our OTP, PIN and even link shared by unknown person. But this QR scan is something new, which I was not aware of, and got trapped in it, as i trusted the OLX organization that no such thing can happen on your platform.
I was trying to sell a second-hand study table today[protected] on the popular sale-purchase online platform OLX. I was approached by an interested buyer on the platform and the two agreed for a deal. The imposter sent me a QR code and asked me to scan it in order to receive the amount. First, he transferred a small amount INR 2 into my account to establish authenticity. Then, debited Rs 3500 from my account in 4 separate instalments - first Rs 1500 and then Rs 1500 and then 300 and 200