Reply to Kontrol S4 Registration and Traktor Pro Upgrade Help

Hey I recently bought an S4 off of ebay and it arrived at my house with flight case and all, but when I tried to activate and register it it said it was already registered to someone else. Now I do know that the previous owner needs to unregister it from their name and all but they gave me their login info and my Traktor won't update because I still don't have the colored waveforms and all that stuff. So if anyone could help me I'd really appreciate it!