THE PROJECT THAT Mills Corp. proposes to build on Piers 27-31 – a prime piece of San Francisco waterfront property – has always been a trade-off. The way the original proposal went, in exchange for replacing damaged piers in the area, building a new YMCA, and creating new open space, the city would let Mills build a big mall and office park.

That never struck us as a good deal – but Mills has made it much worse. As the company enters the final four months of its five-year exclusive negotiating agreement with the Port of San Francisco, Mills has demonstrated that it can't be trusted to give the public a straight story – about its contracts, its figures, or its real intentions for the land.

In fact, this entire project has been a mess of secrecy and misinformation – and when it comes back to the Port Commission Dec. 13 for amendments, it should be killed for good.

First proposed during the backroom-dealing days of the Willie Brown administration, the Mills mall has become a public relations fiasco for almost everyone involved. Mills has embarrassed the Port of San Francisco and the YMCA – and then tried to blame it all on the hired help.

The YMCA was supposed to get a new facility in the project – but the nonprofit would have to raise $30 million. In the end, it turned out that Mills and the Y didn't even have a written contract. And it wasn't until Nov. 29 that port officials finally realized the damage being done to the city's reputation: That's when executive director Monique Moyer finally challenged Mills over its approach, concluding a letter with the huge understatement, "Mills Corporation's recent actions may have undermined the public's confidence in the Port."

In response, Mills CEO Laurence Siegel pledged to do better – by firing political consultant Eric Jaye and public relations spokesperson David D'Onofrio. His Nov. 29 letter continued to dodge responsibility and blamed city leaders, including the supervisors (who voted 9-1 against the plan), for "an unfair prejudgment of the project."

Wrong. This project has had every chance in the world. The supervisors concluded for very good reason that it wasn't financially feasible. And Siegel can't just blame his local flacks for bungling it. If this project somehow gets another chance at life from the Port Commission, San Francisco will have to take another great leap of faith and trust Mills – trust that the company won't put the squeeze on the YMCA to rapidly repay its $30 million debt, or force the organization to fill the new facility with corporation sponsorship logos (as the agreement indicates they might), and trust that Mills doesn't admit any more wishful financial thinking or cooking of the books that would again cause its stock to plummet (as it did last month after just such revelations were made public) and leave San Francisco holding the bag for a project badly or partially built.

The bottom line is that we would have to trust a company that has proved itself untrustworthy again and again. This one is a slam-dunk: The Port should refuse to allow any changes or extend the negotiating period and send Mills packing. For good.