No Internet access for months

I have logged more than 5 calls over a long period that my adsl line at my business premises is not operational. This is linked to line ***. Each time a support person comes to attend the call they inform my staff that they are able to connect via a different username. Each time I log a call I explain that my password has been reset but still not able to access the Internet. This therefore means this is not a username/password issue but rather settings or hardware issue. Months have gone by I am paying for a service that I have not received and I am incurring extra costs having to make other means to access the Internet.