Is Nixse a scam, or is it legit?

I no longer have any current investments. I have €16,200 in my account. I requested a withdrawal of €16,000. Seeing that all my requests when I had €25,815.29 in my account they always refused. Let's see what I agree with. Thierry Pellerin

Hello, I have been with Nixse since June, at the beginning everything went well, until today, in November I am requesting a transfer of €5,000 from my €25,860. I am asked to pay a stock market flat tax of 17% on all of my earnings, i.e. a little more than €4,400, with no proof, no written request for payment or other document concerning this stock market flat tax that I would owe them to carry out a withdrawal request on my invested money. It is even written on their site that withdrawals will be free of charge. After I inquired with AMF, the only flat tax paid was that of capital gains taxes which I will pay when paying my taxes on my income. Results like I don't want to pay he blocked my account. I invested €12,450. Today I am at €25,860 so there are plenty of funds in my account. So I think this company is not very serious and want to keep my money. I have proof of what I write.