can a company force payment?

direct tv' is trying to force my son to pay for my old tv bill' from a few years ago' i did not pay then because i did not get the service they charged me for'now they are trying to go after my son' who has his owen account with them . because he is liveing in the same house i was' but he was never on my account at the time . and for the past year he has had his owen account with them and they never said anything to him until now . is this agantis the law? please no smart remarks on this one'