PLANS to have teams of salesmen knocking on doors to sell Wharf Cable TV have been knocked on the head by the Housing Authority. ''There will be no door-knocking,'' Wharf Cable marketing communications manager Max Ho Man-wan said. ''We discussed it with the Housing Authority, and they told us we would not be permitted to do that. But door knocking was only one of about 1,000 different marketing tactics we are planning: it doesn't make much difference.'' Mr Ho said the first sales office would be opened in New Town Plaza in Sha Tin next Wednesday, just days before the October 31 launch of the Wharf Cable TV package. Yesterday dozens of televisions were set up in selected Mass Transit Railway (MTR) stations to show a three-minute video explaining the concept and content of the pay TV channels. ''Three minutes was the maximum allowed by the MTR,'' Wharf Cable managing director Stephen Ng Tin-hoi said. He said that if the TV sets in the MTR were to show real programmes, there was a danger that people would stay on the platform for hours, causing accidents. About 600 contracts for the $198 monthly basic package have been signed, with the company expecting 1,000 households to be on line when the Governor, Chris Patten, flicks the switch at the launch. The launch will include eight channels from Wharf Cable, with three channels - MTV, BBC Asia, and Prime Sports - expected to be available from STAR TV. Plans for the addition of four premium channels from STAR TV are still on the negotiating table. Mr Ng said Wharf Cable and STAR TV were discussing the best time to bring the premium channels on line.