NT arguments against Feng-Shui

There is a very good-hearted aunt, she is a Chinese and also a Christian, who is constantly persuading me to start following Feng-Shui (a Chinese system of geomancy). The time has come for my family to buy a new house - now she is trying to persuade me to follow this system of Feng-Shui even more in order to choose the most "fortunate" house. She even stared visiting some specialists of Feng-Shui (which to me are really not a far cry from fortune tellers) who consult her (of course not free of charge) on the matter as to where I should buy this new house. The other day she really got me and I had a conflict with her. I told her, "Are you really a Christian? Don't you know that this is in fact a kind of abomination before the Lord?" She confronted me with her kind of logical argument: "This system has already helped a lot of people. If it's good why should we not make use of something which is good? Don't you make use of visiting your dentist every half a year? Don't you make use of doing physical exercises every morning? So why not make use of something good here? And how can you be sure that this system is not from God either? How can you be sure that this system is not allowed by God to exist and help humans?" Today she even came up with some examples from the New Testament. First she cited the fact that the Apostles in the book of Acts used a technique in choosing Matthias which is very similar to that used in Feng-Shui (in fact it's a kind of divining using some objects like coins, turtle shells, etc.) She also said that those magi that came to see baby Jesus were following the star, which is also very similar to Feng-Shui. She even said that since I exercise every morning, while Paul said that physical exercises is not so useful (1 Tim 1:8), which means that I am not really faithful toward the Bible in this regard, why not try something that proved to be good long before even the NT was written? She kind of surprised me with these argument. I think some of those Feng-Shui experts gave her them, because I know that she hasn't yet completed reading the New Testament. So, what places from the NT can I quote to her?