You could use something like this
https://www.powersaver.co.uk/product/knight-grade-3-alarm-junction-box-20-terminals-with-end-back-knock-outs-and-spring-tamper-available-in-white-only/
Who was the email from Start by changing the password on your Vodafone account. Use a different password for each site, and enable mfa if the site supports it.
Looks to me like it could be a TRV with a integrated balancing insert, such as a Honeywell Valencia. If that black part in the centre has a hex head, and numbers on it, try undoing it slowly. You should find that the pin travel increases.
It looks like the heat is coming from what are most probably two diodes that are disappearing under that white plastic cover, (Photo of another BDR91 without cover for reference.)