Barons VW- Ridiculous Company Policy

I recently phoned Barons to book my Polo in. The central locking is faulty and I wanted them to take a look. The woman on the phone said she noticed (once I had given her my registration number) that my car was last serviced in 2013 by VW. This is true, however my car has been serviced every year since, just not at VW (Private service). The woman then continued to explain that they could no longer assist me as my car had not been serviced by VW within the last 3 years. How ridiculous? So Barons is willing to turn down a customer because of their car service history? What has that got to do with them in anyway?