Thanks for the replies. Replaced the fuse and it blew again straight away, so I've emailed the letting agent. They're usually pretty quick, and no heating/hot water gets put on 24 hour call out so should be done tomorrow. The gas safety check was definitely official, received a copy of the...
I have a Vokera Maxin 24E central heating boiler in my flat, and twice now its blown its fuse (a 3A fuse - blew once last month and just there now, about a month later).
The hot water also takes ages to heat up (two minutes or more), although the central heating works fine. Our letting agent...