Mr Garner is one of a number of people who told BBC Radio Manchester they were thinking of relocating businesses as a result.
Joe Devereux-Kelly, who runs a children’s sleepwear business from a warehouse on Liverpool Road, said the regular delays in traffic were “massively frustrating”.
“I sit down and think how much time is it costing people and how much money is that costing in terms of economic input and output?” he said.
Roadworks in Deansgate began August, with new cycle-lanes and a one-way system introduced in a project that has yet to be finished.
Mr Devereux-Kelly said he was moving his business out of the centre in the next six months as a result, adding he felt entry and exits routes into the city had to be reviewed for traffic to flow freely.
Mr Garner said Deansgate should be returned to a one-way system as adjacent streets had turned into a “rat run”, while emergency services were also caught in queues.
Ms Rawlins said the city was changing as the council worked to “improve transport links for people who walk, cycle and use public transport”.
She said this included Deansgate, which would be “completed in the near future”.