If batam, sometime buying ferry ticket at the counter will be much more cheaper. (unless you going during weekday, some ferry has online promo)
http://www.singaporecruise.com.sg/index.php/leaving-singapore/ferry/ferry-operators/
if I am not wrong, Amaris Hotel is at Nagoya hill. You can take ferry from harbourfront (vivo there) and alight at either harbourbay ferry terminal or batam center ferry terminal. Check with hotel if they provide free shuttle pick up from the ferry terminal otherwise you have to take cab there (think IDR50,000 to IDR55,000)