6Hp26 harsh 2-1 downshift - possible solution (at least one of them)

[kvc]

Originally Posted by Doru

So if you consider servicing the transmission, after changing ATF, seals, etc, update and re-flash the mechatronics module, followed by updating the software for the ASC module. The results are stunning.

the ASC updating takes about 1/2 hour with SSS progman.

For someone who has little knowledge about this process, could you please provide a step by step list of what I should do? I have already serviced the transmission (filter, seal, fresh ATF followed up by another drain & refill). The only scanner I have is PA soft which I've used on one occasion only.
The PO had the alternator changed over, just before I purchased the vehicle and said that the battery had gone completely flat at one stage. This lends me to think that a re-flash of the mechatronics is required, along with anything else needed to get my ZF six speed to work as it should. I have no idea where to get the software/re-flash or update for the ASC module. Are these readily available on the internet or can someone please provide them? All suggestions/advice gratefully accepted.