Research supermarket credit

As far as I know, many supermarkets in Brazil offer credit via special cards. I'm interested in the following data.
1. What are the top 10 supermarket chains in Brazil and their market share? Probably can just find online.
2. For each of the top 10 supermarket chains, have a look at their cards, try to determine whether these cards are affiliated with banks or other credit companies. Possible sources of information:
• cards themselves (logos, text)
• printed materials that come with cards or advertise cards
• supermarkets' websites
• supermarkets' apps
• supermarkets' apps' descriptions in App Atore/Goole Play
• ask supermarkets' call centres
• ask supermarket employees in stores

Please, be flexible.
• If you cannot find top 10 supermarket chains, but top 5 chains take up 80% of the market, then it's enough.
• If my price for this project seems too low, don't just walk away, suggest your price.