Heated mirrors not working

[Vivid Victor]

2010 Opel Astra J A16XER.
Heated rear window works fine, the mirrors don't at all.
I checked fuse F6 in the engine bay and it is okay.
I checked the heater resistance and both sides are about 10.5 Ohm.
I measured voltage between the positive terminal on the battery and both the fuse and the both terminals on the mirror and every time I measured battery voltage. Testing to the negative battery terminal yields 0 V, which suggest that there is ground potential on the leads and something isn't switching to close the circuit.
I couldn't find any schematics or diagrams and I don't know what to check next.

[Rusty2009]

There rear only is the the fuse and mirrors.
I'll dig the schematics out later

[Vivid Victor]

Well, it's kinda embarrassing.
Fuse was in position A and I measured that the relay output goes to the most (car's) left terminal - position B.
I honestly don't know how it got switched, but it's working now.