Non Existent Customer Support

We are trying to run an international business with 99% of our customers overseas, unfortunately it is near impossible without a working telephone system. System went down over the weekend now four days later the part required is still in transit, a few hours away by air and the system will not be running until next week. Does this give me the right to reduce my monthly rental by the number of days the service is not available. The entire responsibility is moved to a technician who is on the road all day trying to fix equipment, when little support from anyone else. In spite of logging three service calls I have only had one response, here is your new tracking code, be patient.