Nashua demanding a Service Settlement

We have been with Nashua for over 15 years. We have never really been happy with their machines, or at least their service. This year we decided that enough was enough and that we were going to cancel our contracts with the Cape Town branch. When I requested settlement figures, I was given a figure for the rental and service. When I asked them what the service settlement was for they said it was for the parts and service that they will be losing out on.<br> I asked them how they can expect me to pay for something I have not and will not receive. Anyway their service was so bad and the reason we cancelled.<br> I have paid the rental settlement as well as a good faith amount and requested that they please view this as full and final settlement. They have come back saying that they will not cancel the agreement. <br> I don't see why I have to pay for something that I have not received.<br> Can someone please let me know how this can be legal.<br> Thank you.<br> Shireen