You should speak directly to TC Computing to work out issues with your CUNIX account. They provide us with information regarding eligibility and account expiration for TC students and faculty.

Teachers College Computing & Information Services
Phone: 212-678-3302
Location: 234 Horace Mann (M-F 9-5)
Email: studentcomputing@tc.columbia.edu
Web: http://www.tc.columbia.edu/cis/acs/faq