cannot clear 1471 messages - HELP!

[#1]

Since moving to Plusnet I now get the automatic 1471 answer service on the phone line which I actually dont' want - but as there is no 'Manual' I have no idea how to get rid of it, short of putting 240 volts into the line to fry it permanently (only joking of course). How can I get rid of this 1471 service?
Let's imagine I wanted to keep 1471 answering service, for some strange misguided reason - what buttons do I press to delete all messages so I can get my normal dial tone back? (for it is the latter which is driving me mad)
thanks in advance for your help.

[#2]

It's 1571
I don't have the feature but I think if you dial 1571 there is a menu with various options. Listening to and deleting messages is no doubt a couple of them.
To get rid if the service you need to go to the home 'phone control panel in your PN account and 1571 is listed in the call features. It may be cancelled there.
Someone with a bit more knowledge about it will probably be along to advise further.

[#3]

You can find instructions at http://www.plus.net/support/phone/call_features.shtml
Not sure if you can delete all messages in one go, but from the instructions it looks like pressing '3' while or after listening to a message will delete it.
Hope that helps, alternatively as newagetraveller says, you should be able to rid yourself of the service using the phone control panel.