I have already posted this on tripadvisor, lonely planet and will post to more travel forums because I want to let future travelers to Peru know about these evil agencies: Turismo Sillustani and Acuariu's Travel

My husband and I are traveling for 2 weeks in Peru. Our experience up until Arequipa has been good because we have been following recommended agencies on Tripadvisor and Frommers guide. Our worst experience and this is a valuable learning experience is that DO NOT ever pick a none rated agency because you will be at higher risk of losing your valuables. We just experienced it. We picked a local agency with a big booth in Puno called Turismo Sillustani http://turismosillustani.com/ for a 2D1N Puno to Chivay to Arequipa tour. Because we have had an ok experience so far we let our guard down and trusted the agency. We left our MacBook Air in our backpack locked up and stored in the back of the tour van. The tour was full with 10 ppl total. The first night was fine. On the second day, there were a few occasions where the whole group plus the tour guide were away from the van for sightseeing in the Colca Canyon. This is THE problem. No one was guarding the belongings. The bus driver named Jimmy was on his own. And yes, our MacBook was gone after the tour was finished and we were back in our hotel. We were furious and called the tour company. Our Spanish was poor and they weren't being helpful at all. Luckily, we remember seeing a section about Tourist Police in the guide book so we called and went to a local office in Arequipa. The officer Jorge is very helpful. He called the company and went to their Arequipa office with us. The one we went to was either a sister company or a partner called Acuariu's Travel http://www.acuariustravel.com/ who took care of the Chivay to Arequipa portion of the tour. The staff there definitely got nervous and started calling their boss, our guide named Vanessa and the driver Jimmy. And ha, what do you know. They then said oh yes, they found a laptop on the seat. Right, as if my laptop can magically walk out of my locked bag. You can tell that the staff was nervous. They said the driver was already 45min away washing the car on his way back to Puno but would drive back. We waited 20+ minutes and the boss came to deliver our MacBook. THANK GOD. We never thought it was even remotely possible, we were desperate and trying our luck. We even thought that the Tourist Police could be another corrupted unit. But wow, we got it back. We really could have demanded a refund but we were so glad to get the laptop back that we just wanted to leave.

The lesson is: No matter what agency you choose, always carry your valuables with you. Or, don't bring any with you to begin with. Do not believe in locks. In fact, locking your luggage only increases your chance of getting things stolen because it shows that there must be valuables. And you are better off choosing an agency with ratings because at least their reputation is visible online. Lastly, the Tourist Police is there for a reason. Don't hesitate to reach out.

Hope the above helps.