Do I repair or replace my Samsung cool n cool fridge freezer?

No but your decision, could be compressor you could contact Samsung ask for cost of a compressor. Or personaly would give it its last writes, put cross marker in a rememberance corner of your garden it deserves it at that age.and buy new.
If you are in UK search and read up on six yr warranty rule/law retailers don't talk about. Its if say your new appliance went ape and stopped working or some other fault out of manufactures warranty you still are covered up to its end of six years old. They have to prove it wasn't faulty at time of sale. The instore extended warranty you can most likely get cheaper elsewhere but do you really need to pay out when you can fall back on the six year rule! Search internet you will find all you need on these warranties and law. You no longer have to take their instore extended warranty at point of sale, you can return I believe up to 30 days but check. If you can use the six yr rule why get one put the money away for the unexpected repair after its more than six yrs old.
Re-search, re-asearch, research, then buy, is the rule nowadays hope this helps you to decide.

Bob uk
February 2017