Well my current battery is still just about hanging In, just when it's cold it is slow to crank.
I've always replaced my own batteries on my previous cars which never more than £100, local autolec bit of banter and get a good deal (normally upgrade to heavier duty one).
The under the seat looks a bit of a faff but no great shakes, I think I have even found a battery on ebay that is the right spec,
Varta G14 type 019 for £180 next day.
Or
Hanko battery which says is same spec quality as G14 and listed £140 delivered. (Not sure if this has BEM code)
So it's just getting it coded, can imagine Audi would want £300 plus for complete job and have looked on RAC website which appear not to offer battery replacement for Q7.
Maybe I check my current battery ratings and buy like for like?
Or I got to my local private garage and get them to plug in and code, guessing half he labour at about £40 ish????