Reece Armstrong from Staines and Tarelle Thompson from Croydon were convicted of kidnap, with Armstrong also guilty of GBH.
Levi Burton from Leatherhead was convicted of sexual assault, while Sebastian Love from Merton and Lorna Swyer pleaded guilty to kidnap.
The victim was held and abused in Reigate and Farnborough, with ransom demands later made to his brother.
Sentencing will take place in February.
