Done the test, exactly the same result - rsap does not work...
Downgraded to 4.0.4 (I9100XWLPT) and then upgraded to 4.1.2 (I9100XWLSW) via Kies. Did a total clear of the handset and cache before I started. Still no luck, connects, asks for permission and the 1-2 seconds later disconnects.
Double checked with a Nokia phone and different sim cards just to make sure, made no difference either, behaviour is just the same
Not sure what else to try... Any suggestions most welcome.