I have been with TPS for a few years for both my landline and mobile and it's worked. I just received a call on my mobile from a PPI company. Their telephone number was not hidden and I asked the girl for the company name and where did she get my number from. She quite politely and honestly said they get the number from a company they buy information from. I proceeded to tell her the information was incorrect as I have never had PPI on any loans or credit cards and then told her I was with TPS and to remove my details.
With the information I had, I've reported them and it feels good.