Probably that's because you live very close to your 奶奶同老爺? I purposely moved out from the area they live so that they have to call before coming...heehee
Reading all your messages, I guess I am the lucky one. 99 can only travel by MTR/KCR, and that's why she can't get to my place easily. She just calls everyday, and my husband will handle all the calls.
Before I moved, I used to live very close to 99 and she always comes to my house even she knows that I don't need to work on Sat. She always pretended absent mind. That's why I decided to move before having bb....