Karenjane

Hi all, I have a 2005 WRX, I have recently had the rocker cover gaskets replaced, after about a week and a half the smell of burning oil hadn't subsided, I checked the oil to find it was critically low, I took it back to the garage who say that there was a kink in one of the seals they replaced, they say they rectified this and thoroughly checked. I'm still smelling oil though once she's up to temperature, also this morning she struggled to start, this has never happened in 15 years, someone has told me to take her out for a good blast but i'm now worried this might cause further damage, i'm at a loss at what to do, losing faith in the garage, any advice would be really appreciated.