This questioner is positioned with authority and power in a professional context.
An elderly relative's mental illnesses cause stuttering and awkward behavior that probably explains her often being selected for further interrogation and luggage searches, where she often encounters reviling customs agents (in Canada and UK) who interrogate her on too personal questions, e.g.:
Why are you taking medicine? Why are you refusing to tell me your specific illnesses? Why are you being so uncooperative?
Tell me the names, addresses, and employment information of all your doctors, family and friends. You're being evasive, and I don't believe that your illnesses are causing your behavior. If you still don't answer, I'll flag them and get them questioned too. Then you won't only have a problem with me, but with them too.
After they ask the first time, she will politely decline with the following:
Sorry, but I don't wish to answer these personal questions. I am exercising my right to silence. I will no longer answer questions on the same topic.
My medicines are clearly and correctly labelled by a pharmacy and with my doctor's names. I have nothing further to add to what I said. The same question was already asked and answered.
But these answers are ineffective and sound too brusque, offensive. So what else tactful should she say?
The agents only repeat the question, while intensifying their threats, aggressive harsh tone, and their angry ferocious appearance and face: all which causes her to break down and cry, before she calls one of us or they finally allow her entry. Such interrogations' effects are grievous: her illnesses are then worsened, last much longer and in some cases remain for days.
The customs agents ignore her requests, or invent excuses, for her requests for a supervisor. They'll allege that no supervisor is free, or ridicule her request by asking why they should fulfill her requests if she's not answering them.