PE Supervisors

Please, share how you chose and approached your supervisor to sign off PER. What are the options for those who do not have a qualified supervisor? Another employment?

In my past and current jobs both direct supervisors [finance directors] are not certified accountants and though both are willing to sign off PER & time, they cannot do that for PER.
I approached an external accountant who reviews year end accounts for both companies that I work for and handle the whole cycle from processing sales/purchases to preparing year end accounts. Yet she gave me a lecture that approaching her is inappropriate and she got very angry when I pointed out that ACCA allows to countersign, providing that a direct supervisor signs as well. She was very arrogant and aggressive, stating that annual reviews are not enough to assess my experience. She has been using my work to file accounts with HMRC for 3 years, and should be familiar with my work but refuses to acknowledge it and not willing to review my statements.
Anyway, I am not sure how to handle the situation. Even how to handle a job search if my only reason of changing employment is to get PER signed off. Should I discuss it during the interview? What if I find a job where my supervisor is a qualified accountant but still refuses to sign off as this is a personal favour.
thanks for any ideas