Does IBM ISL revise the offer with a counter ?

Received offer from IBM ISL. Received a better offer after that.

1. Need to know if IBM ISL can revise the offer.
2. What are the cons of renegotiating?
3. For 10yoe, 7B band, Kochi location, what is the salary range to be negotiated? (Ignore the current salary)
4. Current offer is for band 7b, does it makes sense to request for band 8 ? Is there any job level mapping with the band ?