Be careful as a few ticket checkers can make mistakes causing unpleasant experiences. My repeated protests fell to deaf ears!
I had to go and speak to Vasttrafik Securitas officers at Norra Hamnagatan (near Nordstan) and convince them of the wrong decision by the 2 ticket checkers.
Epilogue: Västtrafik is the agency responsible for public transport services involving buses, ferries, trains, and the Göteborg tramway in the county of Västra Götaland, Sweden (plus Kungsbacka Municipality). The Vasttrafik public transport services are usually impeccable and customer friendly, no doubt about that - it is such incidents that create a whole lot of headache once in a while!