pre pago

Hello NOS this is my phone number 93*******, I had mundo livre and then i changed the tariff that cost 7,5 Euro and 500mb internet but after that there is a problem i am neither able to browse the internet anymore and i called customer service and visited NOS store they told me they cannot help with prepaid sim card, i called customer service but no one spoke english. this is utterly disappointing. KINDLY help me and activate my tariff and internet