Fiona MacFarlane was a door-to-door sales representative in the business of selling computers and all their peripherals. She was especially good at convincing elderly people of the usefulness of computers for them. She approached the home of Mrs. Mackay, a retired elderly schoolteacher, where she talked to her and convinced her to buy a powerful computer, a scanner, a printer, and a digital camera. Because Mrs. Mackay wanted to send pictures to her grandchildren, she wanted immediate delivery. Fiona said that the only computer she had that was that powerful was the one she had already demonstrated. Mrs. Mackay agreed to take that computer at once with the scanner and digital camera to be delivered later. Mrs. Mackay told Fiona that she was anxious to have a digital camera in order to take pictures right away. Fiona assured her that she had made the right choice and went out to her van to get the printer and all the peripherals necessary to hook up the computer. As Fiona was returning to the house, she was stunned to see Mrs. Mackay's old blind dog barge into the cord to the computer sending it crashing to the ground. She felt very sorry for Mrs. Mackay but pointed out that the deal had been reached and presented her with a bill for the computer. Five days later the scanner and digital camera were delivered. When Mrs. Mackay tried to hook up the scanner to another computer (one that she had just bought from a local computer store) she found that the scanner wouldn't work and that the digital camera had only very limited functionality. It turned out that the particular scanner purchased from Fiona could only work with the model of computer that Fiona had been selling. Mrs. Mackay went to the expense of going to her local electronics store and having the camera modified so that it could work with the computer she had bought. The printer was suitable to be used by any computer and was compatible with the new computer. She then discovered that the reason that the scanner wouldn't work was that it was a "grey market" product meant for use in another country and it was not capable of being legally sold in Canada.

Mrs. Mackay refused to pay for the computer, the scanner, or the digital camera and insisted that Fiona take them back.

Explain the legal positions and liability of the parties.