Sometimes people who want to work in Sweden receive fake job offers, or sometimes employers do not follow the rules. A fake job offer means that the job does not exist. The employer not complying with the rules means that the job is available, but the employer is not delivering on their promises, for example on salary/wages or conditions.
It is always the Swedish Migration Agency that decides whether you will be granted a residence and work permit. A company or an agent cannot promise that you will be allowed to work in Sweden.
If you are granted a permit to work in Sweden, the Swedish Migration Agency can revoke your permit if the conditions of your employment are not fulfilled. If there has been false information about the terms of employment in your application, the Swedish Migration Agency may also report this to the police.