After talking with the owner on several occasions today I can assure you there was no charge on your bill for any entrance fees, only two lots of people ate food in the bar during the time you were there. Both reciepts were checked so I hope your post can be amended.
From what most have posted here it doesn't seem that you should have been charged for the entrance fee. I would advise asking for a receipt next time and showing the owner if you believe you are being charged for something you shouldn't be. I'm sure he would be more than happy to address any concerns you might have with the pricing and take care of any staff that might be overcharging customers. I believe in at least giving the owner a chance to make it right. My girlfriend will be eating there for lunch or dinner sometime soon and getting pictures of the place for me to add to the showcase page. Should resolve any questions about the entrance fee. I have not given her any information other than "Go eat at Bambulo." She has never been to the restaurant before so she has absolutely no prior opinion of the place.
Went there this afternoon and it turned out to be a mistake from both side. One item on the bill was not in accordance as priced on the menu and I thought that what I did order for diner was lower priced than in reality. It was pure coincidence this caused a difference of 160 peso, reason why the link to the entrance fee was easy to made. So they definitely did not charge entrance fee. Should I have checked the bill more secure the correction could have been made right away. Well everybody knows how it goes sometimes when you get the bill, in a glance you take a look if all items on it have been ordered without taking further notice to each item individually about the price. Sometimes I do, but this time I did not. The staff and I could both laughed how it happened. They refund me the difference. I ordered 2 drinks, had a chit chat with the owner before I went home again. Going back there again for sure.
The girlfriend tried to go today but they were closed. I'm sure it was posted here but I failed to relay that information to her. She will try again later this week.