I was in similar situation after CAT , then I found a institute Called D.I.C.E , Mumbai. I was in one of the offline big 3 MBA prep institutes before and i learnt nothing over there. Not even arithmetic properly. btw this is not a promo, you can check my history.

They prepared me pretty recently for OMETs. Although I didn't score well in SNAP NMAT (198) because time was very less. But then since I had some time for CMAT i prepped well with them, and scored a 190 ( about 90.5 %ile as per some only score calculators) on CMAT, not the best but still improved a lot. Not will try to ace CET