Infill drain cover advice needed

[Gelec]

Hi
I’m looking to use an infill drain cover to hide the drain in the patio. 
The current drain cover is on a 45 degree angle to the house and the drain shaft is on an angle. 
Because the drain shaft is a rectangle brick shaft (instead of circular) I can’t just adjust the angle of the new drain cover. Setting the infill drain cover on an angle creates a lot of extra cutting of slabs.
Any suggestions or tips anyone??