Shaun, your Turbo has most likely blown. There is a design fault on the Renault 1.9 DCi engine and when a turbo blows, it causes damage to the engine, resulting in engine blow by (compression gasses escape past the piston rings into the oil sump and contaminate the oil) this results in excessive oil consumption and insufficient lubrication of the turbo which results in early turbo failure of the replacement turbo.
The worst part of this is that a valve on the engine (EGI valve) which returns unburned fuel back into the system is known to stick initially, and cause turbo failure.
Once the turbo goes, the entire engine needs to be redone with new piston rings, especially when you have engine runaway as you have described.
Best bet is sell the piece of junk and NEVER buy another Renault.