Balwin engineering fees issues

We are unable to complete the sale of our property because Balwin apparently have not paid their engineering fees for one of their developments in Greenstone Hill. City of Joburg refuse to issue rates clearance certificates for anyone selling their property now, until Balwin pays. This cannot be legal...holding an owner at ransom because of a dispute between the two? Can this be resolved urgently. Its been over month and this is the only thing keeping us from transferring the property to the new owners and lodging at the deeds office.