2017 RS6 High Pressure Fuel Pumps replacement cost

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My 2017 C7.5 RS6 Performance has recently been proving reluctant to Start first time, when the Engine Temperature is Warm and I detect the smell of Petrol when I open and smell the Engine Oil Cap.
It Starts no problem, when the Engine Temperature is Cold and my suspicion is that the High Pressure Fuel Pumps need replaced.
Can anyone give an estimate of how much this will cost?… the RS6 is covered by Full Component Audi Extended Warranty Plus Cover.
Thanks for any feedback.