Exchanging money in La Paz is more challenging these days. The banks I normally use will no longer exchange U.S. dollars for pesos. We have to use a cambio, or money changing service.
I am told this is a government regulation to stem the flow of drug money, but cannot confirm it. It seems to happen periodically. One time the banks can’t/won’t exchange my dollars, the next time they will.
Cambios collect a commission for their service, so you are not getting the best rate on your exchange. Today they are exchanging 12.5 pesos per U.S. dollar, while the bank rate is 13.28. If you exchange, say, $1000.00 U.S., the difference is over $60 US.
It may be worth your while to check with your local bank a few days before your trip to La Paz. Our banker at Chase said they need 48 hours to order pesos and will exchange at the bank rate.