This agency has a standard policy of only allowing 3 poly fails before revoking your conditional access. It’s a suitability thing related to your SCI and congresspeople will not be able to help, it’s agency policy that they have no say over. Your contract has the option to say you’re high value and can request to submit you for a 4th poly but they have to explicitly request it. Your current employer can keep you “employed” to keep the process going while you go get a temp job in the meantime.
I had the exact same situation, failed 3 polys and got walked out. Luckily, the contract really needed/wanted me for the role and submitted a request for a 4th poly that I passed but I could not work on that contract while waiting. It took 4 months for me to get a 4th poly scheduled and taken and read back onto the contract.