Previous RS5 owner here.
Big fan of Ravenol (I used RCS - but I spent a lot of time at the track pushing hard) but honestly the best approach is just regular oil changes on time, don't skip.
Also, let's see some pics.
Similar thing happening to me.
Submitted September (with WFH claim), they requested additional docs and I submitted the following day. Escalated 3 times since then with no definitive timelines.
I received my refund yesterday but they requested even more supporting docs at the same time and...
The battery recoding can be done by anyone with VCDS or OBDEleven.
The Audi battery will come with a sticker that has the serial number you need to input, not sure about aftermarket ones.
Example of doing it on OBDEleven with a B8.5 S4 here: