Sneaky Mother

I guess I'm posting this so I can vent my frustration. Today my mother, who has been living with me since June of this year,had an appointment for a colonoscopy. She did the first part of the prep yesterday early evening and then about 9 pm I caught her eating chips! I don't think she had eaten very many. This morning I had to get up at 4:30 to start the rest of the prep. She told me she did have a bowel movement last night. I know through the evening she kept saying she didn't have to go so I figured during the night it would kick in. Prep in morning, still she didn't go.. She said she had one bowel movement but it was formed. We go to the appointment and they say they can't do it today because the colon probably isn't cleaned out! I don't know whether to believe her or not about the bathroom! If she thought she was going to get out of the test if she said she didn't go, she's wrong. I'm waiting for the doctor to call me back to see if they can do it tomorrow, after more prep tonight. I had to take today off and now probably tomorrow or some other day. She lies about alot of things and I don't know when to believe her. I guess everytime she goes to the bathroom I'll have to go with her. Any suggestions? thanks for listening.
Deb