Beaurocracy is rife in government departments, so turn it to your advantage. Post your payment by cheque, but don't sign it. If (and it can be a big if!) it comes back, re-send a second ceheque, but date it 12 months in the future. If that comes back, send another cheque unsigned and undated, and if it still comes back, they are on your case, so send in a cheque, but not the Notice, but quote the Notice Reference Number in your covering letter, but transpose a few digits. Any / all of these methods cause mayhem in the number-crunching departments, and may work. If they fail, all you've lost is a few stamps and envelopes, and you've gained a warm glow because at least you've taken on The System.