Shit really? Man can't catch a break no matter what doctrine you chose. Did the chance of the howitzer dying at least go up when you called in the ability with more munitions?
I actually did kill a howitzer in a recent game I had;
http://www.coh2.org/replay/36541/2v2-breaking-the-meta-with-okw
Mhm. I hope Relic removes the ability for you to build howis in base, or gives them lower range. So you could actually push and kill it with AT guns or tanks.