HI, My First post- hope somebody is patient enough to help!

My 5 yr old John Lewis ? Electrolux Fridge Freezer (frost free) is leaking water onto the floor at the back. The water is dripping off the freezer metalwork above a white box bolted to the frame, around which the power leads are channelled. The drainge pipe is correctly postionned above a water collection tray above the compressor.

I assumed that the drainage hole in the fridge is blocked, and condensing water has found another route out of the chassis.
I have located what I think is the drainage hole on the back of the inside of the fridge; there are sloping channels leading into it and indeed there was a small plug of ice in it. However when I removed the ice I found that there does not appear to be any hole leading out of / from this drainage point.
I've had a good closeup look at it with a torch, and it simply seems to be a small, round shaped recess in the fridge back-plate with nowhere for any water that might flow into it to drain to.

Would be glad of any advice,
Thanks,
Jon