unbelievably rude callers

I was in a car accident 3 months ago. .. i was unable to work and could not pay my account. This morning someone called me regarding my outstanding account. I explained that i couldn't pay but i will be able to pay half of the total outstanding end of feb and other half end of march so that my account can be closed. The lady who phoned me from a unknown number and didnt tell me her name was so rude after me trying to explain why I didn't pay and told me there is nothing she can do and droped the phone without making any arrangements with me. First of all why is it a private number and second of all who is she to drop the phone. Unbelievably disappointed