H1b visa stamp - 212(a)(9)b2

Hi, I had an H1B Visa Stamping interview at Mumbai Consulate. I was initially on L1B visa which expired in Feb 2021. My firm got my H1B petition and got my change of status approved in Oct 2020. I have a 797A document with i94 stating my validity till Oct 2023. However the consulate officer claimed I illegally overstayed on my visa and worked illegally over a year and handed me 212(a)(9)b2 and state i have a 10 year ban in the country. Was this correct and how can it be overturned?