I just finished the Santa Cruz Trek wich I booked with Monttrek and I was really unhappy und felt unsecure.
The nature and the trek itself where amazing, that I can recommend, but not Monttrek.
The guide didnt cared aboput the people. 3 out of 9 people had problems at the tour (feeling dizzy, couldnt see anymore, felt sick and that above 4000m in the rain, with wet stones and steep walls.) The guide just went in the front and never looked after the people. He never checked if everyone is ok and even after he knew that people felt sick, he just continued as usual
The guide allways went in front and left people behind. 4 people got lost on the trek and arrive 1 hour later at the camp ground. the guide didnt care about that.
In 3 days he talked to us in total 5 sentences. He never explained times, tours or what we see arround us.
Furthermore he lied to us in a very bad way. He did a mistake by camping verz close to the river even ity was raining very hard. Next day all tents where under water and all stuff was wet. The donkeys couldnt carry the heavy stuff and he told us that due to the weather we can not continue the tour. After we said thats OK, but we want our money back, it WAS possible to continue and we had a wonderfull day.
Maybe it is just this guide who is terrible. The only thing he felt responsible for was going in the front and showing the way- and even that he did not good.
So my recommendation is, go with someone else.