I found a security hole in an organisation in the UK with many employees. Login form sends user name and password in clear text to the public facing IP via HTTP. Initially I pointed this to IT but they didn't understand and asked for screenshot. I used a sniffer to show my user name and password, on our guest WiFi network which does not have access to the internal network. I didn't use ARP poisoning.
The IT responded to my request saying that they are aware of that and will not fix the problem in the nearest time. IT also reported me to the Head of Security due to the fact I used sniffer.
Q: What shall I do? What are the consequences of using a sniffer within an organisation in the UK?
Talk to boss rather than reporting it directly to IT.