Bring a list. Embarrassment makes everyone forget things, including you.

You are not imagining it and you are not being difficult. Document it and take the document in.

Written confirmation email after every phone call. Cheapest insurance there is. Currently on a scanned-as-delivered parcel myself.

Small wins count. Walking to the mailbox is a data point.

Test one thing at a time. It feels slower and it is the only way to learn anything.