S4_Cinci (I S'edTFA)

supposedly needs new heads! It has been leaking oil with the commensurate burning oil stench filling the cabin and making everyone nauseous. It has been in 5 previous times for this problem and each time they replace either cam adjuster or cam cover seals and burning smell comes back within a week (it has 76k miles on it). The Service Writer said this time they think they've found the problem - a plug in the head that is leaking oil and this problem requires both heads to be replaced to fix.

What the hell is this plug and why would it require both heads to be replaced? I'm under full warranty - VW gave out a 10 yr/ 100k full powertrain warranty back in 2000, so VW has footed the tab and the dealer is being great - free loaner cars for every repeat visit (all except the initial one). The bill for this has to be HUGE! I'm on day 5 and counting with the current loaner, it will be at least 3 more days before they can order, receive and swap out the heads...

Thanks for any technical input you can provide!