Yeah, that does sound a bit too pushy. There are people who lack some common sense, maybe she is one of them. Maybe she doesn't even know it is bothering you. I think you should try talking to her and telling straight out, since she doesn't seem to be getting the hints. Perhaps you can tell her that you like to sleep in and that you like to plan other things to do on your day off other than babysitting. I'm sure you won't hurt her feelings if you tell her in a nice way. She will probably get more hurt or mad if you keep ignoring her calls, plus it is always better to be honest about things... At least that's what I think