Button functionality recognition

On our website we have a section with the top sales products of each brand. The sections are headed with a big title. Clicking each brand top sale button shows a group from five up to ten different products.

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The problem: nobody interprets the buttons as such, they continue navigating without knowing by clicking on each button the products of the lower part change.

Adding each brand logo worsens the design by the difference in shape and proportions of each:

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What can be done to make this function more evident? I guess it's a design problem.

Other data:

  • It's possible to change the button's shape, style or color

  • We can not use different colors for each button

  • We can not show the products with a rollover on each button, it must be a click.
  • The buttons are inside a responsive flexbox
  • The five default products displayed when loading the page belong to the first brand button
  • Only show five at a time, the products are in a static jssor slider with a Show More indicator