The situation you're facing is indeed complex, and the potential actions your company could take largely depend on the company's policies and the legal framework of the country you're in.
Firstly, it's important to understand that if the erroneous transaction was a genuine mistake and not a deliberate act, your company should ideally not hold you solely responsible, especially if there were no clear guidelines or training provided to prevent such errors.
However, if the company decides to take action, it could range from a simple warning to a formal reprimand, or in severe cases, legal action to recover the lost amount.
Regarding your resignation, it's unusual for a company to refuse to accept it. Generally, an employee has the right to resign from their position, and the company cannot force you to stay. However, they can hold you responsible for any losses caused due to your actions during your employment.
In this situation, I would recommend the following steps:
1. Review your employment contract and company policies: Look for any clauses related to errors, financial responsibility, and resignation. This will give you a clearer idea of your rights and responsibilities.
2. Consult with a legal professional: Given the potential legal implications, it would be wise to consult with a labor law expert. They can provide advice tailored to your situation and the specific laws of your country.
3. Document everything: Keep a record of all communications and actions related to this issue. This could be crucial if there are any disputes or legal proceedings in the future.
4. Communicate with your company: Try to have an open and honest conversation with your supervisor or HR department. Explain the situation, express your willingness to cooperate, and discuss potential solutions.
Remember, it's important to stay calm and professional throughout this process. Mistakes happen, and how you handle this situation can greatly impact the outcome.