Manager held me hostage over my bank card

I am very disappointed by a guy who presented himself as a store manager at Exact store Carnival Mall. Yesterday I went into the store to make an account payment, I was to use my bank card which I have used in another store 5 minutes ago. When I got to the pay point, I could not find my card. I told the person who was helping me that I cant find my card but I had it with me when I entered the store. After looking for it for few minute I gave up an use other means to pay. "The manager" was standing there as well, which I will assume he had what was going on. After few minutes of leaving the store, I got a call from exact and they said I must come an collect my card, the store was already closed. I had to turn back as I was already on my way home. When I got to the entrance, the " manager" was just in the entrance and I stood there for about 10 minutes without him opening to find out why I was there. He went to the tills, i could see this as the door is see through, he fetched my bank card and eventually opened the door. That suggests that he new I was the card owner before I even introduced myself as he was there when I said I cant find my card earlier. When he opened the door, he said he needed to verify my identity before he could hand over my bank card to me. Because I did not have my I'd with me, I suggested that we do security checks on the system as the store had my address and I'd number on the system. He refused and gave me an attitude. And also that how they new it was my card because they went into the system and into my account without my permission. He told me that he is going to destroy the card if I do not present my Id . That when the argument started and every staff member in the store claiming that they are the one who found the card. I fetched the I'd, came back and presented to him and he refused to take it, I snatched my card from his hand and he locked the door and told me I was going to stand there until morning. After a long argument and me asking him to let me out, he said I needed to sign some papers which was never presented to me. He said I was not going to take my card out of the store. After several attempts to ask him to let me out ,he opened the door for me and I let him keep my purse with everything. He never gave me anything to sign. I am currently without all my belongings. To cover his back, he called his area manager and **** to her.she called me and told me that the store is about to close and they have my bag. She could have gathered the correct information before she called me. Exact needs to find a way to get my purse to me,