ACC has confirmed 201 formal complaints from clients have been laid about taxis not showing up or arriving late.
Drivers have confirmed they were paid up to 10 percent less for an ACC job, so some would ditch it for a better offer if they could.
Rachel Scott had two stints of ACC in the last four years, both marred by days of Auckland Co-Op taxis arriving up to an hour late or not at all.
Drivers told her it was because they were paid less.
Adele Holmes, who has been on ACC twice in the past two years, had the same experience with Auckland Co-Op taxis and said drivers confirmed it was because they were paid less.
RNZ was contacted by 16 clients who echoed similar stories.
However, ACC said the figures prove overall, the service was good.
A spokesperson said the complaints were over a nine-year period, so totalled a very small portion of the total rides clients would have taken.
"During that time we funded more than 3.3 million rides so the percentage of complaints to total rides was 0.006 percent.
"Every ACC client deserves a reliable taxi service and ACC treats all complaints seriously and works hard to ensure problems are fixed so that clients aren't inconvenienced.
"On the basis of the data it would be incorrect to say ACC clients face a poor service when the overwhelming majority of rides are completed satisfactorily."
However, ACC acknowledged there were likely to be other complaints not picked up in that figure.
"As our search involved a free-text search of client feedback identified as complaints, the figures provided are by no means a complete representation of the number of complaints ACC has received relating to taxis.
"This is because complaints can be made, and dealt with, through a number of channels."
ACC said from April 2016 it had better record-keeping of complaints and could confirm that 87 percent of complaints from that time onwards, related to Auckland Co-Op.
ACC's existing contract with Taxi Charge, to which taxi company Blue Bubble - the umbrella group of Auckland Co-Op, is a member of - is coming to an end.
Taxi Charge is a third party billing system which takes a higher transaction fee, the more often drivers - who are independent contractors - choose to settle their account.
ACC, along with 11 other government agencies, tendered for new taxi contracts last year.
ACC's client travel services will be provided by NZ Taxi Consortium while Blue Bubble and Super Shuttle have contracts for ACC corporate travel. The other panel member, Driving Miss Daisy, provides companion services.
The new contract is for three years with two rights of renewal of two years each.