I have the same issue. When setting a program to record, I select the option "Save Until Space is Needed", rather than the other option of "Save For 1 Year", yet programs are deleted after 1 year even thought it shows I used 35% of available storage. This looks like a Xfinity programming flaw that they need to either correct or give their customers options to download programs they want to keep into a separate hard drive.
We appreciate you writing in and letting us know about the problems you are running into with your recordings. I use my DVR to record my favorite shows so I can watch them back whenever I want, so I know I wouldn't be too happy if they disappeared on me. We'd love the chance to help out with this to make sure everything is working as it should for you. Can you please send me a private message with your first and last name along with your full-service address (including any apt numbers)? To send us a private message, please click on my name <ComcastKatieMS>, then select "Send a Message" on the right side.
The problem could be that you are assuming that "Save until space is needed" doesn't really mean, "Save for one year unless I am out of space before then, in which case, it can be deleted earlier." To be fair, if this is the case, then it would be Xfinity's fault for not making this clear, especially as the other option is "Keep Until I Delete" on other services.