One morning, Bea was looking

[Bassim]

Have I made any mistakes?

One morning, Bea was looking for her camera, but was unable to find it. She immediately accused her cleaner, Linda, of theft. Linda, who had been working for her for years, protested her innocence, but was unable to change her mind. Linda felt deeply offended and left, refusing to take the pay for the job she had done. Next day, Bea opened one of her bags, and there, at the bottom stood her camera. Her face burnt with shame. She knew Linda wouldn't come back even if she offered her millions.

 

[abaka]

One morning, Bea was looking for her camera, but was unable to find it. She immediately accused her cleaner Linda of theft. Linda, who had been working for her for years, protested her innocence. But Bea would not change her mind. Linda felt deeply offended and left, refusing to take the pay she was owed. The very next day, Bea opened one of her bags; and there, at the bottom, stood her camera. Her face burnt with shame. She knew Linda would not come back even if she offered her millions.

'Linda' restricts 'cleaner': no commas.
But Bea....: This really should be its own sentence, for two reasons: (1) to avoid momentary confusion about who "she" is; (2) to emphasize the crux of what follows.
Pay she was owed, the very next day: idiomatic phrases.
Bags; and there: I'm permissive about comma usage, but here the semi-colon adds the short pause that enhances the sense of contrast.
Would not: Bea's solemn acceptance of the unhappy truth is best expressed formally, without contraction.

Even if she offered her millions: this is your conclusion; I hesitate to change it. I would point out, however, the idiom would not come back for all the money in the world.

Bassim, your English is excellent. All of my changes concern subtle improvements of style.