You can also use their "call back" service here; - http://www.halifax.co.uk/bankaccounts/callback.asp

Works for me every time, and I give them an 0870 number to call me back on  

I don't know. I was given the *01 tip by an HBOS person when I complained and it works. Worth trying on other systems and see whether it works. Zero often bypasses menus but usually puts you thru to a switchboard so may be a false economy whereas the 01* does go thru to customer services.