The aux battery in the way must be the biggest moronic excuse for not doing oil change. 99% of Patrols have them fitted. What is probably happening is that if you were to pay for full retail service there would be no issues.
It just shows what sort of dodgy offers these dealerships will come up with. Do it yourself, learn about the car and feel good about saving some cash in the process instead paying some dopey to do it.

Cheers