BMW poor customer service

My Navigator on my R1200RS was giving problems so I took it to BMW Cedar Isle Motorrad. After a month and 2 weeks they come back to me and say sorry can't help you without the original invoice for the purchase of the Nav. Now bear in mind, during this month and 2 weeks, I had to phone them to get updates, not once did they phone and keep me updated. I also told them I was going on tour middle of Sept and needed the Nav back. Now at last minute they say.."sorry can't help you". What poor poor customer service and attention. Can't believe this is the service you get for buying a premium brand....