BQB received its first jet aircraft, an A320 leased from Vueling of Spain, on 28Nov13. The plane, c/n 4661 and registered EC-LLJ, was delivered to Vueling on 14Apr11. This is the same aircraft that was leased to Andes Lineas Aereas of Argentina for a short time in late 2011/early 2012.
It is presumably leased to BQB on a wet-lease basis, also known as ACMI (aircraft, crew, maintenance and insurance provided by the lessor) as the plane will be returned to Vueling after only four months at the end of March 2014.
BQB used the A320 to introduce daily service on the Montevideo (MVD) - Santiago (SCL) route on 15Dec13 but researching the carrier's website reveals that it is also being used on some of the carrier's flights to Sao Paulo Guarulhos (GRU) and also occasionally to Florianopolis (FLN) and Rio de Janeiro Galeao (GIG).
Photo of the new addition to BQB's fleet in Vueling colors with BQB titles: