Suzuki Swift 2006: Servicing scams

With my wife's 2006 Suzuki Swift due for its 30,000 km service I phoned around and got quotes from a number of Suzuki dealers and was astounded to find they ranged from $295 to $501. Why do the prices vary so much for the same work? I was also informed that when the rear wheel bearing locking nuts and wheel bearing caps are removed they break and that the owner must pay for the replacement parts. Surely this is a design fault and should be paid for by Suzuki. What other product breaks when it is being dismantled?