My merchant account was closed. No explanation given. They have a large sum of my money and told me that they are not giving it back ever. Is this normal?

My account was reviewed recently in order to increase the amount we are allowed to process in payments. Or so that is what they said. I responded and provided all of the information they asked for. Was told it would be two business days they did not respond via email like they said. I had to call and ask for the information. They stated that an email was sent, no such email exists from them. A representative verbally told me that my limit was increased. Taking the word of the agent I proceeded to process another payment. They now have closed my merchant account and are holding 15k and said that I will not receive the funds. Meanwhile they have not put anything in writing at all no information on how to resolve the issue or how my client can resolve the issue. They simply closed the account and said too bad. Meanwhile they charged me $180 for my subscription that I am now forced to keep open. This doesn’t seem fair. They have not asked me what type of service I provide or anything, they are treating me like I have done something wrong. I am at a loss and now have to explain to my client that they are holding the money and will not release it.