When You Wish Upon a Star, a charity for sick children, received an email from Mike Law of Lloyd-Law Associates asking for items such as car stickers and pin badges.
The charity tried to speak to Law but was told he was unavailable. However, his company repeated its request for materials and said: "We are professional fundraisers."
When the charity said it did not employ fundraisers, it received another email from Lloyd-Law's office manager, Mrs B Percival, saying the company wanted to become a donor, not to fundraise.
It said it wanted the information for a survey of charities' compliance with donor requests, which it claimed would be published in Third Sector and sent to the Charity Commission and the Fundraising Standards Board.
"This is a serious survey and there will be consequences for those charities who have failed the survey test," the email added.
Karen Martt, general manager at When You Wish Upon a Star, said all she knew about Lloyd-Law Associates was an email address, a mobile phone number and a postal address that turned out to be a tile shop in Lytham St Anne's in Lancashire.
She urged charities to be cautious about sending out letterheads or promotional items because they could conceivably be used to copy charities' identities or to fundraise without permission on their behalf.
Lloyd-Law Associates did not respond to requests from Third Sector to say what its business was. It said in an email that it had requested donor information packs as part of a charity survey.
"It is everyone's right to request items from a charity in return for a donation," it said.