The company said Mr Heaslip accepted the allegations at a disciplinary meeting, and explained his wrongdoing was due to "personal issues".
Hayward said it had no alterative but to terminate his employment, which Mr Heaslip had accepted was the only appropriate response.
Other issues about Mr Heaslip' performance were raised but never put to him.
Police had written a letter of complaint about his driving, while GPS data from the coaches showed he had gone over the speed limit about 400 times.
However, only the five customer complaints had led to the decision to dismiss him.
Mr Heaslip told the ERA he was not given a proper opportunity to respond to the allegations against him, and denied they were true. He argued the company did not undertake a proper investigation and he was treated unfairly.
He also alleged the company acted improperly by giving him further work after his dismissal - including driving a coach from the South Island to Auckland, and transporting a group of elderly patrons.
But the ERA rejected Mr Heaslip's grievance, saying it preferred the company's evidence.
It said a good and fair employer was entitled to dismiss Mr Heaslip when faced with his "frank admissions of wrongdoing in relation to each of the allegations made by a series of complainants".
The ERA also brushed aside the issue of the extra work, saying the company had "felt sorry for Mr Heaslip" because he was out of work and short of money.