2012 Vauxhall Corsa 1.2 Ecoflex losing power?

I keep losing power with this. I've had the car 12 months now and the service management light keeps coming up. I contact the garage and they say I need to drive it more and to get the revs up as much as I can. Still the light comes back. Today the car lost almost all of the power, took about 60 seconds to get to 20 miles per hour. I decided to bring it to the garage and just as I was about to pull in it sounded as if my tired popped. Turned out it was the engine and a pipe had burst. This car has a lifetime warranty (clearly needed) so the garage got the pipe fixed. They said I wasn't taking long enough journeys which causes the filter to block up which is why the car lost the power and the pressure got so great causing the pipe to burst. 12 months with the same problem yet they say I don't drive it enough. I drive it every single day on long distances. Are they fobbing us off?