Foz do Iguaçu (IGU) to Porto Alegre (POA)
 

I have to go from Foz do Iguaçu (IGU) to Porto Alegre (POA) in July 2018. When I checked the fares, I saw that the prices in July are (R$ 384) almost double as that of prices in April/May/August. Is it due to the vacation season? Am I missing any cheaper options? If I use some miles for this sector, will the prices be same during all months? If so can anyone suggest some mileage programme that I can enrol and use ( for this purpose) ? I see that the bus journey will take about 20 hours. Is there any interesting places for a stopover ( to break the journey for a day trip in between)?
Thanks,

Yes, July is the school holiday season in Brazil and Foz is underserved in terms of flights (and is one of the country's prime tourist destinations). I don't know what your circumstances are, but R$384 seems to me like an ok price to avoid a 20h bus journey, especially when the latter costs R$200 (or R$350 for sleeper service). There is nothing of interest along the way.

In terms of using miles, Azul is the only one to fly this route direct (currently 13k miles). They aren't part of any alliances but have a partnership with United. Avianca flies the route via GRU but it's 20k miles and therefore poor value.

Having said that, you can find flights for R$279 on www.maxmilhas.com.br which is an award ticket marketplace (reliable and tolerated by airlines, for now). You'll probably need a Brazilian-issued credit card to buy a ticket here.

The price the OP quotes for July is about equal to similar distance flight in the USA (maybe Boston to DC).

Thanks a lot RafKa for telling me about maxmilhas . I could see some amazing fares there.
I also checked United miles requirement; it is flat 8K miles for all months. But "United members will receive five base miles per dollar".
Just to clarify: I was not whining about the fare; I was surprised to see that the fare for July is almost double that of the fare in the months before and also after.

Now I see that maxmilhas ask for the CPF while registering. I have some friends in Brazil. Can they book ticket for me or is it mandatory for the traveller to have CPF.

Do they have a credit card, and a clean credit history with the SPC? Are all their ID numbers current (and have they voted, which keeps some of these up to date)?Don't assume this is true of any and all Brazilians.
I have had friends in Brazil book domestic flights for me in the past, but directly with the airline. I have also booked from home with all the ID details of a kind Brazilian friend, but there are many ID numbers and dates needed iirc (and even most Brazilians may not be aware of all needed, to anticipate).
A foreign visitor can travel in Brazil without having to present a CPF while in transit.

Frankly for the BRL100 difference between maxmilhas and buying direct on Azul (and getting 5 miles per USD) I would take the "peace of mind option" and book it myself. Too many moving parts otherwise.