So, am in Brazil in December 2017. Both São Paulo and Rio de Janeiro. First tip - even though the Monzo card is a debit MasterCard, when you go to pay for something you’ll be asked ‘debito’ or ‘credito’. Always say ‘credito’ and your transaction will go through smoothly.
I’ve had ATM issues, I haven’t worked out the correct routine yet, but will try today. Either the transaction is declined or it says my daily limit has already been reached. Monzo support have been great, especially where an ATM charged me but didn’t give me any money.
ATMs here a really sophisticated. First, you push your card into the slot and remove it. The ATM offers you a choice of languages and one of four accounts to withdraw money from - Checking, Credit, Savings or Universal. As it knows your card has a chip, it will ask you to reinsert your card and enter your PIN. You choose how much you want to withdraw and then wait. I managed to withdraw some cash from a Banco do Brasil machine selecting Universal, but I think I was just lucky.
The ATMs and many large shops and supermarkets have gone biometric - they have a thumbprint sensor for extra security. Luckily, being a foreign card, it doesn’t need that.
I’ll post again when I have found a successful ATM withdrawal method.
It is a good idea to have a working smartphone with data so you can monitor what’s happening and to chat with support. I brought my 3 phone which counts Brazil as a Feel-at-Home country so I can make and receive calls from the UK from my allowance, same with data. Seeing as most Brazil mobile providers give WhatsApp free, most people will message you and make calls using it.
Alternatively go to a Claro or Tim shop and buy a SIM (take your passport) and if no one in the shop speaks English to activate it, both providers have English helplines to get you started.