Blocked account

Someone from Capitec sent money (R3k) to my Standard-bank account on the 15th of February 2024, and I don't know the person. Then the next day capitec informed standard bank to block my account instead of reversing the money, n they did not even inform me. Now am stuck and I do not have access to my account because of stranger. When I call standard bank they tell me that you guys are busy with investigations.. What is it that ur investigating because you can just tell me to return the money so that I can have my account bank? What you guys did to me it's so unfair