Hi murrill,
I am not sure what went wrong there but I had done a Tamiya Mobelwagen which is somewhat similar to the Wirbelwind. I used Tamiya Dark Yellow as base coat and it worked just fine. If I remember it right, the plastic is of yellow color already so I needed only a light coat.
Adding more paint to your kit to catch the correct color may do more damage as you will drown some important details like panel lines, rivets, etc. If you don't want to strip it, you may just try to compensate with a dark-brownish-weathering wash and dry brushing (with correct dark yellow color) to come close to the desired color schemes.
If you have the patience, you just as well strip the paint off.
Good luck.