You could report this to the administrators of the site, but in the likely event that the e-mail is picked up by customer services it's unlikely to be understood.
Hopefully it'll be elevated to a development team who will hopefully understand it.
However you may wish to urge caution as if it's grossly misunderstood you don't want to be accused of hacking.
Alternatively in the UK for example the "data protection act" is legislation to protect against such mishandling. The "information commissioners office" handles complaints. In particular there is statement on the gov.uk site to contact the ICO if:
Make a complaint
If you think your data has been misused or that the organisation holding it hasn’t kept it secure, you should contact them and tell them.
If you’re unhappy with their response or if you need any advice you should contact the Information Commissioner’s Office (ICO).
https://www.gov.uk/data-protection/make-a-complaint
The ICO is a useful resource: https://ico.org.uk/
The UK is particularly good and I suspect other countries have similar legislations in place, however certainly other countries aren't as forthcoming.
