I spent roughly 3.5 hours of taking the HU out moving the wiring harness up and down/into the corners pushing the Hu back in. Every time i would get the HU back in but it would not go all the way in. My hands were too chunky to be ale to pull through the harness through climate control vent so I tried using needle nose pliers to pull gently the wires - all of this did not work.
I got my cousin to come help me as he has done many car audio installs and he tried to no avail. In the end we decided on cutting a small section of the plastic cage to the left hand side at the back which the quad lock could be pushed further down into the footwell. As a result the HU slid back in taking some effort as space is very limited.