Anyone knows of any tingkat service which allows us to choose only 3 times a week instead of the usual 5 days?

You can consider this: http://sg.foodmatters.me/subscribe This allows you to choose how many meals in a month you would like, minimum is 4 meals per month. If you want 3 times a week, you can choose the "Light" option for 12 meal credits a month. Unfortunately, this is not exactly "tingkat" and they only do lunch time delivery now. Not sure if this will be suitable for you. One other tingkat service I've found is Mom's Cooking (http://www.momscooking.com.sg/pricing/) which offers a 4 day option.