The decision has led to River City Cabs asking clients such as Willis-Croft to get off their scooter and climb into the van.
For Willis-Croft that's no easy feat.
He suffers from chronic lung disease and is very easily short of breath.
"We've got to get off them and then walk around and then get into the van.
"I stress out quite easily and also [after] just a short distance and I'm out of breath," he said.
Willis-Croft was adamant all the journeys he'd had were perfectly safe.
"Maybe the person who's from Horizons should go in the van for two or three days and just see what it's like. They might get a better idea of it then."
The person Willis-Croft was referring to is Desley Monks, the transport planner for the Total Mobility Scheme at Horizons.
"It's always been the case," she said.
"The taxi companies probably have recently had a realisation of how important it is to make sure passengers are secured safely in the back of the hoist stand."
Monks said the hoists taxi vans used to lift wheelchairs were not designed to take the scooters.
"Mobility scooters come in a myriad of different sizes and shapes and brands. We don't have a standard so therefore it's very difficult to make a call and say yes mobility scooters can go in the back of vans when we don't know for a fact they can be secured safely."
She commended River City Cabs for buying wheelchairs for customers to use.
"They went out and bought wheelchairs so that they can take people that are not permanently in a wheelchair but do need a mobility scooter.
"It took the onus off the drivers."
Monks did admit the move left people in mobility scooters in a difficult position.
"We do feel that it's something that needs to be looked at, at a higher level.
"It's not something we can make a ruling on.
"We can see that a mobility scooter does need to be transported but unfortunately we don't have the control to change that at the moment."
Noeline Lane is the president of a group of mobility scooter users known as Pedestrians on Wheels and she has asked for an explanation from Horizons.
"It's discrimination against the disabled," she said.
"You take our mobility scooter away and for some of us it's like taking our legs away."
Lane will get her explanation when Monks visits the Pedestrians on Wheels on Wednesday, May 16 at the Brick House Restaurant. The meeting starts about 1.30pm.
