As a different law applies to universities of applied sciences (Fachhochschulstudiengesetz, FHStG), your studies are not automatically continued by paying your tuition fee if you are studying at a university of applied sciences and a university at the same time.
If you are required to pay a tuition fee at your university of applied sciences and the University of Vienna, you have to pay twice (including your Students’ Union fee).
If you are required to pay a tuition fee at your university of applied sciences, but only your Students’ Union fee at the University of Vienna, you have to pay your tuition fee (including your Students’ Union fee) at your university of applied sciences and your Students’ Union fee here.
In case you have paid your Students’ Union fee twice, please contact the Austrian Students' Union for a reimbursement.