How can I get rid of ATT?

I got DSL from ATT and they hijacked my Yahoo mail account. Now I can't turn around without seeing the ATT logo whenever I'm accessing a Yahoo service. I am a Yahoo mail user of long standing and do not want or need ATT between me and Yahoo. I'm willing to pay for Mail Plus if it will get rid of this arrogant companys' logo. Please help. If no solution I'm changing to GMail. Thanks.