Mike Street says he experienced disbelief, horror, then panic when he realised that an InterCity bus had departed Levin without him.

The Whanganui man was travelling to Wellington to have his recently installed cardiac pacemaker checked when he asked the bus driver if he could use the public toilet in Levin.

"Levin was only a drop-off and collection point, so I told the driver that my medication required frequent visits to the loo," said Street.

The driver told him that he would allow two minutes which Street took to mean that he should be as quick as he could.

"Unfortunately, both toilets were occupied, meaning a wait of two or three minutes."

Street says around five minutes had elapsed by the time he headed back to where the bus had been parked.

"It wasn't there - I'd been left stranded, with my bags, books and coat on the bus."

A police officer contacted InterCity and arranged for Street to travel to Wellington on the next bus and for Street's daughter-in-law to collect his belongings and meet him at the bus depot.

When Street's daughter-in-law collected his belongings, the driver told her "We waited and waited. He didn't come back, so we left".

Street said he is especially offended by the use of the word "we".