Browser Hijack removal desperately needed.

My girlfriend’s notebook has become infected with a browser hijacker. I’ve tried running antivirus programmes (Avira, Advanced System Care, Malwarebytes' Anti-Malware, Super Spyware Remover) but nothing seems to touch it. I even tried using a different browser but the problem remains. Normally I would just restore the notebook back to factory settings but it was a free gift she received when taking out a new phone contract and didn’t come with a restore disk. I really am at my wits end. Can anybody please help me? I've installed Hijackthis and can proivide a log if required.

Thank you.