Got a quote from Britelite windows, gave them our details. Asked explicitly for reassurance that they wouldn't pass on our phone number. They gave us that assurance. A few weeks later, got cold-called in the evening by Thomas Sanderson (the blind company), trying to sell us their blinds. They stated that they had got our number from Britelite windows who had sold them our number. I will be contacting Britelite to express our disappointment and needless to say will not be using them for our work.