Brokers Hill House Hammond (HHH) are listed for a hearing at the high court on Monday over a dispute with Motor and Legal Group.
The case is believed to concern proposals by HHH to change the administration arrangements it has with the Manchester-based motor claims company.
A recent round of meetings held by the Vehicle Builders' and Repairers'
Association has raised worries about the growing market power of larger insurers in the industry.
Addressing this point, Simon Mayhill, claims director at Norwich Union, said: "We believe we have a good relationship with our authorised motor claims network. We have managed to make sure the relationship is beneficial to both parties."