Even with 1 link i think you will struggle to get any service work from lex. They have their own service centres, cant remember what they are called, but they want everything going through them or dealers. i had a family members car in for service (a lex vehicle) when i sent for auth they declined and said driver would have to re book with one of their centres via their booking team or use a dealer. I said customer had taken day off for this service, didn't make any difference.
I'd still have a go though because sometimes with these companies, the progress you make often depends on who you get to speak to.

Steve.