August Clearing is only for filling 1st year places.
No University will be interested in messing about with 2nd year places in the middle of Clearing.
If you want to switch Unis, you need to email them now, with full details of your A level grades, and ask if a transfer is possible, and then apply asap through UCAS if they say yes. Just remember that they will want your UCAS reference to be from your current University.