They then asked for a sysdiagnosis from my mac, I declined as I do not know what information that diagnosis contains.
You can see an overview of what sysdiagnose does by looking at it's manual page: open Terminal.app, and type
man sysdiagnose
Quote:
---
What sysdiagnose collects:
o A spindump of the system
o Several seconds of fs_usage ouput
o Several seconds of top output
o Data about kernel zones
o Status of loaded kernel extensions
o Resident memory usage of user processes
o Recent system logs
o A System Profiler report
o Recent crash reports
o Disk usage information
o I/O Kit registry information
o Network status
o If a specific process is supplied as an argument: list of malloc-allocated buffers in the process's heap is collected
o If a specific process is supplied as an argument: data about unreferenced malloc buffers in the process's memory is collected
o If a specific process is supplied as an argument: data about the virtual memory regions allocated in the process
---
You can look at the exact files that are collected yourself.
Open Activity Monitor, select View > Run System Diagnostics. The process will probably take several minutes, then a Finder window opens that shows the content of the invisible /private/var/tmp folder. There's a .tar.gz file called sysdiagnose_... (with the date and time of the data collection). You can copy it to the Desktop, and open it by double clicking. This shows you all the data that the process collects, including log files, etc.
The data collection is local, on your computer only, no data are sent to Apple (or anyone else) during the process. So you can review the collected files, and decide if there are things you don't want to send.
Looking at things like the System Profiler report, logs and top output are standard steps when tech support looks at a complex problem.