Hi to you from David, 'The Famous Forry'
This is a classic sympton of the system being short of gas.
It is repairable in most cases and requires a re-charge of gas. The gas leak will need to be found and sealed but is often a very slow leak and a special leak detection kit is needed.
I have regased and it has worked for 2 years plus with no further problem on several occasions.
You can do this yourself but for a one off repair it will cost you about £25. You will then have enough gas to do the same type of repair a dozen times over.
How do I go about fixing it myself and where would I buy the Gas that is needed?
You would need to go to a refrigeration sales place in your area. Firstly look on the rating label to see if the gas is R600a or 134a. Most modern systems run on R600a so if it is as new as you say it will be this gas. So you then go to store and buy, Gas Cartridge, Cartridge Valve, Charging pipe, and Bullet piercing valve. You now have the equipment to re-charge the system. I will explain further if you decide to but the materials above. Best wishes, David, 'The Famous Forry'