Any idea why my 2012 Audi A6 has a startup issues?

What is your question?

Every time I tried to start it up it's cranking but it won't turn over. if I waited for about maybe 10-15 mins it can turn over but if I drive say 15-20 mins and let it sit about 10-15 mins then I have to restart the whole process. On my dash looking at the RPM, the redline will be all the way at 4,000 RPM. I've tried recharging the battery as well and still the same... Not sure if its a starter issue? or alternator issue?

What makes this problem better or worse?

It's worst when it's cold

How long has your 2012 Audi A6 Quattro had this problem?

Quite some time