I had the same problem. Emails only resulted in replies sending me to the website to look it up but since I didn't have a bill number, etc. and which is why I was emailing (sigh). So I tried to call one time before I went down to city hall. I admit I was on hold for almost 15 minutes but the representative was able to find out the amount I owed (with interest), the bill number, and also found out the address on file was my old address. (I've lived at new address for 4 years.)

She submitted a 311 ticket to update address and I went online with my bill number and paid.

(804) 646-5700

Before going down there try calling, and prepare to stay on hold for awhile but it beats going down there.