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 (FH) and a university at the same time.
Some FHs forward on to the universities that the Students' Union fee has been paid there. This forwarding is not yet carried out by all universities of applied sciences. If you pay at the FH: About a week after the payment, check u:space > Financial Matters> Tuition Fee/Students' Union Fee to see whether the Students' Union fee has been reported as "received". If this is the case you can re-enrol your studies at the University of Vienna via Studies > Study Overview. If the Students' Union fee has not been reported as "received" and there is no incorrect payment at the FH, the payment will not be forwarded by your FH. You have to pay at the University of Vienna again.
The following applies:
Regarding the reimbursement of the Students' Union fee paid twice (including insurance), please contact the Austrian Students' Union directly.