baumatic br27b fridge freezer icing up in the fridge

hello there,
model br73r
i was called out to this a intergrated frost free f/f the fault was to cold in the fridge the back wall was biulding up ice but it had a good square ice patten i found the door not sealing well and corrected this and defrosted ice nice easy job !!!
not 3 days later i was called back still the same iced up again in the fridge i suspect the module or temp sensor is faulty but decided to check the back from the compressor the pipework was freezing up i suspect this is just because it is running so much??
ive had this pipework ice up when cowboy engineers put too much gas in the system but the customer hasnt had anyone else out to it.
what do you know?
can anyone give temp sensor resistances?
do the modules go?
model br73r