It may be a good thing that you did not go through the IRS hotline before you have consulted with a lawyer who could study your case and suggest options that are better for you. You can request the IRS to reinstate your agreement, or file an appeal if you think that there is an error in the computation of your taxes. Tax laws could be complex and it may be quite difficult at times to deal with the IRS yourself. It would be better to work with a tax attorney who could guide you and represent you in dealing with the IRS. Take note that you must act immediately because you only have 30 days to respond to the CP523 notice.