Battery Tesla or Varta

As for the battery choice, I'd personally opt for the Varta. The main reason being the service life you have received from the original battery. I wouldn't worry too much about the Varta's lower rating as the original has seemed sufficient over approximately 6 years and most Phaeton owners are reporting excellent life from the original batteries.

The battery is very clean and the original Varta and the box is in tact. Car has about 42K on it, and has been in service for less than 3 yrs.

The cells on the original Varta battery have 6 caps, 5 of which are located under the stickers on the battery. Peel the stickers off. Your dealer hasn't been doing this right. Now, put on some goggles and some gloves. Take a quarter and turn out each cell cap and set them aside, someplace clean and someplace that you wouldn't want damaged by battery acid. Just a precaution. Look inside each cell. You should see the vertical plates, and they should be completely immersed in water- submerged about 1/4\". If not, add distilled water unto each cell until they are as such. It'll take only a couple of ounces.