overcharge for not existing services

comcast charge me the balance of $281.97

for the billing period , from 12/10/2008

to 01/09/09 , in the mean time I request disconnect the service on 12/09/08 because they raise the charges ffrom $145.96 to $281.97 which mentioned above they cut the service the same minute I called untill 12/27/08

Again , The period of 12/09/08 to 12/27/08 I did not have any bussiness with them

after many phon calls I have the service back on 12/27/2008 for almost the same rate I have it befor $ 158.00 almost , January, and February 2009 had been payed , but comcast still bill me for the period I do not have service with them the amount of $281.97, I tried to contact them many many time by phone , and by email but no body care all what I got is promise to investigate the account and get back by explanation , and correction , I am very disappointed , and I am not happy because I was wasting my time when I spoke with their Customer Services, and all what I get acumulation of the bills carring the same fals charge of $281.97 , please I need some body who care solve that and get back to me by mail thank you