One of the men, 37-year-old businessman Juan Liedeman, was to have entered a plea and sentencing agreement with the State.
Liedeman, who is out on R20,000 bail, faces a robbery charge relating to Heyns’s stolen vehicle.
However, his lawyer William Booth was not in court because of a knee injury and the case was postponed until Thursday.
His co-accused, brothers Marthinus and Sarel van der Walt, will remain in custody.
The brothers have been charged with killing Heyns and robbing him of his car and other possessions.
Heyns, a University of Stellenbosch medical professor, went missing last May. His body was found in a shallow grave in the Strand the same month.