External winter vent covers for Duetto

Ok, I want to get the vent covers which go over the external Electrolux vents, where is the best, cheapest place to get these from?

As a side note, I get this draught (if parked into the wind) coming from the bottom of the cooker, is that vent related? Where is the vent for the cooker?

Hi
Are you sure the draught is from the cooker when we had a Duetto the draught in that area came from the heater vents built into the seat base, the blower side was piped to the heater but the suction side had no pipe to it and as the heater unit needed an external vent in the floor the wind used to blow like crazy through it, our solution was not to use the inbuilt heater and block the vents up, not ideal i know and maybe a bit dodgy if you happen to forget.