Only got round to contacting them an hour or so ago. Response so far:
Hi Stephen,
We do apologise for the inconveneicne caused.
We can only whitelist the rules as they are triggered as turning off modsec on the account is not something we can do on a shared server. We need to check the logs to see which were triggered recently. It's difficult searching these logs without IP addresses but I found another rule which was triggered today, which I have now whitelisted.
I am not aware of a comprehensive list of modsec trigger keywords but I will ask a server technician tomorrow.
Regards,
[name removed]
Customer Services