I would like some advice please on resolving a problem with…

Hello. My name is***** would like some advice please on resolving a problem with an online travel agent, "Zuji". My husband and I booked flights last November to travel to Brazil, leaving 26th May and 30th June, and returning on the 16th July together. Our son and his wife live in Brazil and are expecting their first child mid-June....We initially received confirmation and e-tickets from the airline, (LAN). Since February, we have received emails from time to time from Zuji regarding minor changes in the flight details. The last change we heard of that was initiated by LAN apparently, was to depart from Sao Paulo, Brazil about 15 hours earlier, which would mean losing another day with our family in Brazil, which we weren't willing to accept, so began negotiations with a proposed departure for the following day, the 17th. So far, tentative flight details have been sent to us by Zuji, but, they have told us that they are still awaiting confirmation from the airline, and so updated e-tickets still have not been issued. I have rung Zuji countless times, spending approx 30 minutes on the phone each time, and still haven't been able to get the final e-tickets...... additional note... added at 12.40p.m. I have just found details of another website where bookings can be checked, and most of the flights are confirmed now except for one leg of the trip on the 17th July, from Sao Paulo, Brazil to  Santiago, Chile (a 5 hr flight), which is showing on the records as cancelled.... Am looking into re-booking this part of the trip directly with the airline if all else fails...  Not sure if the whole investigation still needs to be made now ?? Thanks... Kaye XXXXXX