Issue with HCAD tax valuation

So the wife was looking at houses on Zillow, and decided to look ours up. Zillow had our house listed at 4 bedrooms (our house has 3) and about 100sq feet more than it actually is. On a hunch, I checked HCAD and sure enough that's how it is listed there. We purchased our home in 2018 (brand new), and it's been listed like that since then. How do I go about getting it changed, and am I entitled to a tax refund?