My fridge has a gas leak can it be repaired?

I have a siemens intergrated fridge freezer about 4 year old, the light is on inside the fridge compartment and i can here the compressor running. When i emptied the damaged food from the fridge i noticed a bulge inwards on the back wall about the size of a half golf ball which someone said indicated a leak. i have removed the fridge from its apeture and have noticed that the pipes on the fridge are hidden inbetween two walls? so there is no access to the pipes without doing some damage to the bak of the fridge or removing the back layer. is this possible to be repaired, not by myself by a refrigeration guy or is it a gonner:(