My contract says 20+bank holidays, but our internal policy says unlimited subject to local minimum requirements. It's a small company, so it's an honour system

My contract says 20+bank holidays, but our internal policy says unlimited subject to local minimum requirements. It's a small company, so it's an honour system. I've taken far more than my contractual minimum every year I've worked here, so having to get backpay or carry over hasn't come up just yet.