Good afternoon. I have just joined a new school which specializes in offering business english solutions for companies. I got a new student from one of its clients. She´s a controller and works at Cartier Jewellery. Her english is pre-intermediate but unfortunately she is still talking in portuguese all the time and I would like to know how can I motivate her to lose her shyness and tension in order to feel more comfortable with herself ?

I am using the Oxford books (business result ) and murphy (grammar in use). she´s also weak in grammar but I do not want to focused only on her grammar because she needs to improve her speaking.

The only way is to REFUSE to talk in English to her. Only speak English and refuse to answer her when she speaks Portuguese. If you really can't do that create vouchers that she can cash in to speak English say one per lesson. If you are the teacher then you need to rule the room, in a nice way but also in a firm way.

You also need to assure her that that mistakes are good and the best way for her to learn. I guess she knows her grammar is week an that is part of the problem.. Don't correct every mistake. Pick your battles - correct your TL in that lesson only so she isn't overwhelmed.
I just correct at the end of the class. I use a table called VPG (vocabulary, procunciation and grammar).