Bosch KGN39V00GB/02 Ice in bottom of freezer compartment

Hi, I have a two year old Bosch fridge freezer (frost-free) – just out of warranty by a month. Ice is accumulating in the bottom of the freezer compartment to the point where the bottom drawer will not come out.

I have completely de-iced and tried again but the same has happened again. At one point I could see water trickling down the back – right of the freezer compartment.

I have now removed the back panel of the freezer compartment and the refridgeration tray at the top of the freezer compartment. Enough to poke a piece of coated wire down the drain hole and prove it is clear.
I suspect that there is something wrong with the refridgeration tray at the top of the freezer. It appears to be built in two parts rather than a molded unit and the water looks like it is coming from the seem between the sides and the bottom.

I am not sure it is worth requesting an engineer as the money may be better off going to a new machine although it breaks my heart to ditch a 1 year old fridge. Can the refridgeration tray be end user replaced – ther eseems to be some kind of specialist joint in to the pipes that run around it .

I am also wondering which make to go for next – antoher Bosch on the grounds they should ahve a working model by now?

Any advice greatefully recieved.
Chris