Rhino man you have not done your home work,I have
been there done it WASTE OF MONEY! 
carry on go ahead waste your money,when got loads of sales people call rack your bill up! sorry just been there done it,this will fall on deaf ears :
carry on be my guest! 
Hi Terry - been there done that myself - been in business for over twenty six years. That is why I did my homework!
I know how to deal with the odd sales person who calls me and a few pence wasted here and there doesn't bother me in the slightest.
The number of calls which do come through from commercial clients speaks for itself, as I set this company up in 2010 and we only clean commercial businesses and I have two vans on the road almost 7 days a week.
I am not saying every customer comes through the 0800 number but a decent percentage do.
You may be the worlds fastest window cleaner - cleaning 3 panes of already clean glass, but I am not so sure that you have the knowledge to comment about 0800 numbers. It would be interesting to find out how well you are doing in this business - hopefully you are a multi van operation with umpteen employees - you should be as you have been around for a very long time.