[WCE]

I know someone who did this:
1. next time they contact you tell them that you feel you were mis sold  their product  i.e the free trial and that at no time was any mention of an ongoing contract to advertise with them. 2. Tell them that you will invoice them for anytime spent dealing with the matter further. 3. Tell them that you will be reporting them to trading standards. They will still hassle you so keep in contact and record all dealings with them. Report them to trading standards and then     
You should invoice them for your time that they have wasted since you told them that was what you were going to do. Now you have stalemate. All you do then is send a couple of demands for outstanding payment and ignore them. You wont get your money but they should now leave you alone. If they do take you to court then you will be able to counterclaim against them this is what my friend did and yes it is underhanded but it works. They wont bother chasing your debt because they if the judge rules in your favour  then they could end up losing money. 9 times out of 10 though they are just trying it on in the hope that you will pay them without question.   

[Pole2pole]

Give it a try Dave........It really does work. I aint had a call from any salesman or company for a couple of years since i registered. Unfortunately, it don't stop the double glazing peeps knocking on my door though  :

[Wayne Thomas]

I had them keep phoning and pestering me the begining part of last year, they were becoming a pain in the rear, they won't take no for an answer, so the next time they phoned, I told them I was bankrupt and out of business, never heared a thing since.

I use to get pestered with cold callers until I told them I was renting the property, had bad credit ratings and couldn't get approved for any loans what with all the countless county court judgements against me. Jokingly I asked all the cold callers that I would still be interested in whatever rubbish they were selling would they let me have it on the never, never but they all declined and none of them have ever called since.