I've had very similar problems with the GET/ schneider dimmers. I've removed almost 20 from clients properties and have fitted either 2way switches or MK or similar rotary dimmers. I have had a rep chasing the supplier for an answer to the problem but 6-8 months later I still have no reply( or credit for the faulty gear). The cost to me in terms of labour is running into days and obviously the loss of reputation from the clients who think I've sold them a cheap product!
I have also installed these dimmers in my own home. Nearly 50% have failed in 12 months. They are installed in a range of materials from block through to lathe walls and dim a variety of loads and lamps from halogen gu10's to standard 60w Bc lamps to a 200w halogen. All dimmers that failed had a different load( surprisingly the dimmer working the hardest at 300w is still going!).
i would strongly advise not to fit these dimmers even though they look appealing. Danlers are far superior and work on the same RS 2 wire multi way switching.