I tried AOL once for 30 minutes! When I called to cancel they tried the marketing "why don't you stay" etc... You do you have to stand firm - I found it helped to say "read my lips: c a n c e l m y a c c o u n t...ok?" 4 -digit code promptly issued.
I would also highly advise not to cancel by email like it says it their help file - heard a lot of stories of emails not received excuses.