Wow, just had an exciting/stressful morning in La Paz. We were busy checking out of our Hostel when we realised we only had enough cash to cover the hotel fee but not for the rest of the day. Not a problem, we headed to the nearest ATM a Banco Bisa which we had heard charges no withdrawal fees. Stuck in our Mastercard asked for a few thousand Bolivianos and minutes later were presented with a Error stating that there was a temporary communications error. The machine had only offered 500Bs as a max so we assumed it could be our larger withdrawal request. Its generally better to withdrawal larger amounts to reduce withdrawal fees on both ends, in Bolivia and back home.
Next we thought lets try the BCP around the corner, they had worked well for us in Peru! Stuck our card in again and this time only offered us 450Bs. The machine was working purely in Spanish and after asking for a few thousand Bolivianos it warned us that it would charge 27.44Bs ($4) for the transaction. We had been paying roughly this in Peru so agreed. It wasn't long before the machine presented an error in Spanish warning that something was Invalid.
Next came Banco Mercantil! It offered English or Spanish but soon after requesting a few thousand Bolivianos and no mention of fees except from our local bank we were told we had asked for too much money. I tried again at 800 and 600Bs all receiving the same error. Anything below 1000BOB is not really worth it, vs the fees.
Solutions
We decided to ask the travel desk at our Hostel what we could do. They told us the problem was not the banks but our MasterCards. If we had used a Visa card we would have been fine. Let me just point out that at the Bisa ATM I specifically checked for the MasterCard logo so assumed that all would be fine. Apparently not, and MasterCard does not work well in the ATMs in Bolivia. Luckily we have Visa and Amex cards with us! The travel agent continued and told us, that BNB otherwise known as Banco Nacional de Bolivia works just fine with MasterCard and we should be able to get between 1500 and 2000Bs.
We walked to the nearest BNB24 ATM and sure enough after being warned of a $4 or 27.88Bs fee we walked out finally with some cash.
Success!!!! What a stressful mission, having fears of spending days with no money in Bolivia. I hope this helps any other travelers out there. :D