Roger Gilbert, 76, was chief executive of Fujitsu s UK and Ireland business from April 2009 to 2011, during a key stage in the development of the scandal.
Jacquie El Kasaby and Rose Stewart were told they would be pursued by debt collectors if they did not pay up, despite not taking any funds, BBC Scotland reported.
Will Mellor played sub-postmaster Lee Castleton in the ITV drama, which told the true story of several sub-postmasters across the UK wrongly accused of theft and fraud.
Peter Sewell was part of the Post Office Account Security Team at Fujitsu when East Yorkshire subpostmaster Lee Castleton faced his legal battle in 2007.
Lee Castleton was one of hundreds of sub-postmasters who were prosecuted over claims they were stealing from the Post Office - but the missing money was actually due to errors in the Horizon software, which was developed by Fujitsu.