Debbie,
Register your fax line with the Fax Preference Service - they are in the phone book and I am sure directory enquiries will give you the number.
I was getting bombarded by 'Rightt 2 Vote' dial tones, slimming aids, joke phone messages etc. I registered, and almost oll the junk faxes stopped within a couple of weeks.
Well worth doing and costs nothing.
Andrew