I’m so sorry to hear you are going through this, but please know you are not alone. There are always ways to resolve these types of issues with difficult advisors, it’s just about finding the right approach.
You can absolutely request to have communications be through email(although they may need a call once in a while to confirm identity/proof of life). When I had this issue, I explained that due to my conditions I needed to be accommodated with email communication to give me the time to be able to process and include all the necessary information, and to be able to have a record. If you make it clear that it’s about accommodating your disability, they are more likely to comply, since it would look very bad for a disability company to not accommodate disabled claimants. Just clearly state the negative impact that the phone calls have on your current state, why the emails would be beneficial(ex. “I cannot think clearly when on the phone due to my high anxiety levels, and I would be able to process the information easier though email” or “due to my high anxiety levels, I cannot process my thoughts or information clearly on the phone, and email communication would provide me the time to respond with all the information needed”, etc.), and make clear that the stress of the phone calls are detrimental to your progress in treatment/recovery/health at the current stage(what I assume based on your post).
Also, if you are seeing a psychologist/mental health professional/primary caregiver - I would discuss this and the affect these calls have on you, and they may be able to provide a letter for the company supporting email communication for health benefit, or at least support you in telling them how this is detrimental to your treatment and recovery. This often goes a long way if it’s an option, but I know many people do not have access.
I know it is incredibly hard, and I know how torturous it can be with anxiety, but please don’t forfeit your job and the benefits you are entitled to! As much as they may try and make you feel as if you don’t, you DO deserve this coverage until medically cleared! I know it’s so hard, but you can do this! If you do need to apply for CPP down the road, quitting and forfeiting these benefits may be an issue; but I’m not a lawyer, so I have to defer to David for his advice there.
If they continue to give pushback after the above, ask politely to be escalated to the supervisor. Sometimes if a supervisor sees that you have explained why you need an accommodation, they will make the agent follow it.
Hang in there!