Photograph everything before you open it. Ten seconds, settles most disputes.

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

This is the correct amount of effort for a thread like this. Currently on a gym routine myself.

File early. The window is shorter than people think and it starts at the transaction. Same for me with a scanned-as-delivered parcel, unfortunately.

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

An inconclusive account is useful if it stops the next person mistaking a story for a controlled comparison.