We moved nearly three weeks ago and kept our very outdoorsy 8 year old cat in for the recommended two weeks. We then let her out and she was happy to go, so got rid of the awful little tray (I hated that thing).
A couple of days later my DP installed a cat flap so she could go out and in on her own accord. Problem is, she will not use it. She'd rather wee and shit all over our new house. It's driving us bonkers. This morning I put her breakfast outside the cat flap so she'd go out. It took her ages and took a lot of persuading (I had to hold the flap open for her). But she still came back in and pissed on the landing up against a poster I had just framed and was waiting to put up, which is now ruined 
We don't know what to do anymore. We're tearing our hair out. What is this cat flap fear and how do we stop it?