transmission is doing rough gear changes, slamming into gear on deceleration to lights, and even slipping sometimes/ worse when overheated. Tried some Lucas Oil Transmission fix (bottle with flushed transmission fluid) but didn't seem to help much.

Volvo C70 Convertibles are lemons. Around 100K give or take, the transmissions begin to fail. I serviced the car regularly. I had the computer updates done as they were due. But the transmissions are worthless. I would love to connect with other C70 owners and start a class action suit. This is a common problem and Volvo Corporation is aware. They would not assist me with getting another transmission.