Office is not promoting me in my parent cadre

I am working as an accountant in Accountant General ( Accounts & Entitlement ) chandigarh where in order to be promoted to Assistant Accounts Officer (Group B Gazetted) you have to clear Subordinate accounts Service exam. I cleared my SAS exam in august 2021 then after that there were no vacancies in my cadre so i switched the stream and cleared Subordinate audit serivce exam which made me eligible to go on deputation and absorption in Civil audit offices which is a difference cadre. now my Headquarter Comptroller and Auditor General came up with a one time measure scheme "as is where is " basis where sas passed official will be promoted in the same stations. there are so many candidates in my office who have just cleared sas civil audit exams as they only wanted to go to audit offices. since earlier it has been the practice that a candidate who cleared both exams get to choose whether he wants to go on deputation and absorption and in meanwhile if there exits vacancies in his parent cadre he gets to be promoted in his office. now my headquarter is asking me to join only audit office in same station (Chandigarh) even though there are vacancies in my parent cadre. there are employees previously who after clearing both exam got promoted as Assistant accounts officer. there is no rule that says once you change the stream you forfeit your previous exam. can they deny me promotion in my parent cadre ?