Grand Reserve Chardonnay Brut

I went in thinking either Cava or a very simple - even slightly off - Champagne. Turned out closer to neither, though it leans more toward "off." The nose offers a bit of fruit, a bit of oil, and then a strange whiff of plastic that I can't unsmell. The palate has some oxidation, which would normally be a good thing, but here it's not married to anything - no richness, no real acidity to lift it, just a flat middle that thins out fast. And then the finish: short, with a strange unpleasant bitterness that sits on the back of the tongue and refuses to leave. Sparkling wine that doesn't quite know what it wants to be.