what is going on?? Anyone any ides

Well I am computer iiterate=never saw one till I was 60 and didnt want it then. I just spent 175 in the shop over two weeks. I kep getting a popup stating There is no dialtone check to see if the modem is properly installed. Well a new modem later and another two trips back uptown where they had no problems connecting on their hookups. I told the boy if I swith from tone to pulse I can get on but then I get bumped off within ten minutes. He just stared at me. Well tonight I found out that if my beep alert on the voice mail is activated by calls i havent erased then it wont connect. If I erase all the calls there then I can get on. If someone leaves a voice mail while Im online it knocks me offline. I have Verizon and of course will talk to them on Monday. I feel stupid for I certainly cant afford this bill. Anyone know about this or what might be going on>>