Ok I have no personal experience of this but as there are many on here going through the horrors of augmentation I thought I would pass on the experience of a poster on another rls forum.
He was prescribed naltrexone for a separate issue but found that after he started naltrexone he was able to half his dose of mirapexin from 1mg to 0.5mg (he states himself that he was severely augmented at that stage). He also found that impulse control issues he was experiencing, caused by the high dose of mirapexin, disappeared.
As I say, I can't vouch for this myself but naltrexone in high doses is used to help addicts stay on the wagon. Apparently it works on opioid receptors and his theory is that the naltrexone negates the excessive effect of the augmented mirapexin in some way. Importantly, he does not take a low dose of naltrexone. He started on 25mg (ldn uses something like 3mg) and has reduced to 12.5mg which is still effective for him (these are American doses - I'm not sure if they are the same in the UK).
Given the difficulties associated with achieving a workable regime after augmentation and the calibre of drugs required to afford relief to those with pronounced symptoms, it would seem to be worth trying this in appropriate cases (ie where a substantial dose of naltrexone is not counter-indicated) for people who are experiencing augmentation on dopamine agonist drugs.