Could you not just ask her to feed them while you are away next time? See what happens. At the very least you will be changing something and she is unlikely to say no to your request.
I have been listening to 'How to make friends and influence people' this week. The more they say yes to you the more likely they will be to say yes to you when it is something they might have originally said no about. Worth a try.
M36 W31 S4 S2 T5 M4 BD Jan12 S July12 Recon Sep12-Nov12 ILBINILWY Jan13 OM x 2 in 2013 W wants R July 13 I start D. Jan 14. Meet GF Nov 13 Have I changed enough? Jul 14