Short selling11

Hello, I have bought 33 shares of a company for amt around 150 and after some day I sold it for 170 but again I stop the selling ordered and bid for 172 which got fully executed and now total 66 shares got sold out and I had only 33 shares in my account. representative said that the remaining 33 will be auction on NSE. Kindly help to understand what exactly happening in this scenario and what is the steps.