GE sbs refrigerator freezes.

Hi
I would like to ask for your help and advice. I have (quite an old) GE model TFG30PFDA WW sbs refrigerator. lately, it started to freeze the products in the cooler cabinet. measuring the temperature yield reading of -1 to -2 deg celsius. the first thing to do was to slide the temp adjusting knob (I think that it's not a thermostat actually. it seems to me that it's a damper that controls the amount of cold air coming from the freezer) but to no avail. it's still freezes. looking forward to hear your opinion (beside throwing it out and buying a new one).
Thanx.