For people looking to book online I have just had a really positive booking experience with an agency called Bali Dwipa. I'm not sure if they are the cheapest for all hotels, they were for what we were after, but their service is fantastic. They replied instantly to my emails and, when I questionned if they had to debit my card they phoned me to explain. We had to supply credit card details as surety but dont have to pay until we get to the hotel where one of their reps will meet us.