Hi there,
Unfortunately accidental transfers to incorrect bank accounts are a common occurence.
A good first step would be to contact your bank immediately and inform them about the error. Your bank should then inform the recipient's bank about the accidental transfer.
The process of correcting an error can be expensive. Banks can charge as much as several hundred francs to look into erroneous transactions which have already transpired. Before you ask your bank to correct the error, make sure to ask them how much they charge for the service.
Another difficulty you may face is that the recipient of the money cannot be obligated to repay the money. The recipient's bank is not allowed to disclose their name without their permission, as doing so would breach privacy laws.
If the amount transferred is large and the recipient refuses to repay it, you can press charges against them because the law does not give them the right to spend money which does not belong to them. However, the legal process involved may be time-consuming.
If you can find out the identity of the recipient and they refuse to repay the money, you can file a debt collection case against them at their local debt collection office. This will require some effort on your part, and your chance of effectively collecting the appropriated assets will depend on the recipients ability to repay the debt.
Best regards from Moneyguru