Where could we go or who could we call? We have organised to stay in our own villa so could pay for someone to come to us?
I'm not really into yoga myself but my wife is a bid fan. The times we've visited Bali she's gone/ used a group called Bali Spirit. She found them on the Internet and thinks that they are great. Otherwise most of the hotels and resorts offer yoga and/or pilates sessions too.
Have a great trip! about 8 years ago