Unfortunately, we cannot speak for Comcast, nor do we know how to get in touch with a Comcast technician.
SORBS has not blacklisted YOUR account, per se. SORBS is an IP Address based blacklist (an IP address, or Internet Protocol address, is a unique address that certain electronic devices use in order to identify and communicate with each other on a computer network utilizing the Internet Protocol standard (IP)—in simpler terms, a computer address). So, SORBS is based on IP Addresses. In your case, the IP Address, or addresses asociated with you email address is managed by Comcast. SORBS typically blacklists ALL IP Addresses associated with large Internet Service Providers like Comcast.
Where does that leave you?
One, we do not recomend paying SORBS $50. This will not do you any good. As long as you have an IP Addresss associated with a large Internet Service Provider (SBC Global, Comcast, Charter, etc), there is a good chance that the IP Address will be listed on SORBS (constantly or periodically).
Two, is this limiting your ability to send email? Are you having trouble getting emails delivered to important recipients? If no, then don't worry about it. If yes, then you might consider taking a new approach to your email, which brings us to number three.
Three, if you are a business or professional organization, it might be time to consider a new email solution. A premium, business class email hosting service will solve your SORBS problem and offer you many other considerable benefits. If you are a home user, then you should consider opening up a free web mail account to send to those recipeints who cannot recieve your mail now because of SORBS.
Our email experts are available via telephone to help business email users understand and solve problems like these.