Guess I've been lucky then - in my 25-year old 4 bed house only one mat and one stat have gone!
I just bought ceiling mats for an extension to our house, and thought they were pretty good value - assuming they last the expected 20 years of course! Compared to slimline storage heaters they're...
Eswa have an office in London;
020 7582 4300
I'd recommend having a look at the broken panel to find the part number before you call them - or just measure the panel so they know which replacement you need. Probably worth you checking them all while you're in the loft!
A cheap circuit tester will tell you if the thermostat is working. The heating panels have a 20 (ish) year life expectancy, and in my house all but one have lasted 25 years so far. They're not expensive to replace - if in the loft space you can easily do that yourself. However, if downstairs...