There is now a British Consulate in Recife in Brazil. The contact details for this Consulate has been listed below. Note that the calls do at times get forwarded to the British Consulate in Sao Paulo. This is only a temporary issue. You can call or email them should you not be certain what to do when you are in need of assistance.
If you cannot obtain assistance then contact the British Embassy in Brasilia for assistance. You can speak to them about a British visa such as a partner visa or an education visa for the United Kingdom. You can also ask about the possibility of a passport renewal or emergency travel documents if you have lost your passport while on holiday in Brazil.
British Consulate General Recife