Department of education north west ripping service providers off

They rip service providers off. Received an order from the department in the north west rustenburg to be exact, to provide transport services. Being buses, taxis and a 45 seater. When the time arrived everything was booked and paid for. The department ended up not using some of the transport services and guess what they failed to inform us in time or to cancel some of the transport that they will no longer use. Now trouble started when they where suppose to pay. They refused to pay the full order amount and only paid for the buses and 1 taxi that they used. Dilemma is that what now happens to the buses and other transport services we offered, booked and paid for that they did not utilize? Who's suppose to now lose? We used our money paid for these and they later did not use them. They did not cancel them or change the order or even inform us in time of these changes. We are now sitting at a lose that they refuse to pay. If they did their jobs well and informed us in time before booking and paying for these services we wouldn't have booked what they would no longer utilize. We ask to be paid the rest of our order amount because we paid and booked for these transport services and they later did not utilize them and failed to inform us or change the order. This is what we experience as service providers with this department and they just don't care and don't want to take accountability of their slip up.