Debt collector Harrassment

I had a bill with AT&T for $296.38. The last bill was 10-09. They terminated the service after I tried to put the phone on vacation until I could pay it. Now there is a collection agency trying to collect. They started calling me at work in November of this year. I ask them not to call me at work. They made 3 calls in Nov. One day they call 2 times. I told them to call me at home. Some how they got my unlisted number. The first time they call me at home ws just before Thanksgiving. They wanted me to give them my bank acct. number. I told them I wasn't going to give anyone my acct. #. They said they could reduce my bill amount from $337.93 to $296.38. I repeated to them about not giving my acct. on the phone to anyone. I asked for an address and acct. number and I would send some money. They wanted to argue with me. I said I would send the some money. They finally gave me an address and acct. # but no business name to send it to. So I was going to wait for them to call me at home again to get the Business name. They call me at work again. I told them to call me at home and I would talk to them. Then at work again and told them the same thing. Finally they called me at home. We went thru the same thing about giving my acct over the phone and I said I would send some money. They asked how much and I said I didn't get paid until Friday. I wanted the full address, name included to sent it to. When I got paid I sent them #10 the first week, $10 the second week. Then they called me at work again Thrusday, Dec. 16. I told not to call me at work. I have not heard from them as yet. I want to find out if they can still call me and harrass me if I am trying to pay?
Thank you Jennifer