I have been sanctioned by my country's Higher Education Commission after being accused of plagiarism. What can I do?
Your question is weirdly vague on one important question, namely whether you actually are/were a co-author of the two questionable submissions. I am not sure how one can be "alleged" as a co-author - isn't that entirely clear and a completely black-white, yes-no question? Is your name on these papers?

Even if the HEC does not publish the name of the co-authors, you should still know whether you actually were a co-author of this publications or not.

The question "what can I do?" very much depends on your answer to this.

If yes:

You have presumably been sanctioned correctly. Trying to weasel out of your penalties based on formalities will likely only reflect worse on you. Accept the 2-year blacklisting and move on.

If no:

This then should be a clear-cut case of misjudgement, and following the formal appeal procedure whatever it is should definitely work out in favour of you. Your university should support you in this if the case is actually "I was blacklisted for a paper submission that has nothing to do with me".