WHARF Cable will campaign hard this weekend to sell its pay-television service to Taikoo Shing residents. Sales executives will be stationed in the lobbies of residential blocks to catch people as they wait for lifts. For householders who want to pay $198 for Wharf's eight channels, a team of engineers will be standing by ready to fit the cable decoders within minutes of a sale. Marketing manager Max Ho said: ''If it works then we will introduce the same kind of campaign in other big housing estates such as Whampoa Gardens and Laguna City.'' He said the campaign was launched partly because of the reluctance of the estate's management to allow Wharf staff full rein in carrying out sales promotions. ''They have restricted us to a large extent and have just allowed us those two days to have our sales staff doing open canvassing. So we are making the most of it.''