Havent heard of your problem before but my wives mk6 GTD when the lights are on they flicker up to full and back down again quite a lot , They are on auto all the time so I don't know if its just that or not , have tried on normal and it does it but not as much or at least I don't notice it .
Its due for a service so might ask them to have a quick look .
Good luck finding the fault with the R ...