Wrongly submitted return u/s 139(9) without notice.

Previous consultant of one client intentionally take revenge against by submitting wrong return ( u/s 139(9) without notice of I T). For FY2019-20, where refund was Rs 24000 but after return u/s 139(9) I.T payable was Rs. 95000. Now Income Tax demanded outstanding amount. So how can help client???

Note; Client belong to Schedule Tribes (S.T) where income exempt u/s 10(26).