What reason has the bank given?

What has the bank instructed you to do?

Do you mean both... it's been hacked and afterwards the bank blocked the account?

How long ago was the client transfer? and did that cause a problem with the same bank?

Not sure what 'prosić of fans' means...was he blackmailing you and threatening to involve the bank?

I'm assuming its proof of funds

oh thanks Caledonia

they did not give any reason, they said they could block my account without giving any reason.

bank want proof of funds

everything was ok with the client, it was a long time ago because about 1.5 months ago but I just came to the UK to clarify it

they did not give any reason, they said they could block my account without giving any reason.

bank want proof of funds

everything was ok with the client, it was a long time ago because about 1.5 months ago but I just came to the UK to clarify it

What proof of funds do they want?

I don't presume he's a punter but if the client is a sex client could he have made problems with the bank? Many banks have a morality clause.

It says on their website:-
'Sometimes, we may delay or decline transactions that we think are unusual, or even block your account until we can confirm that you’re making the transaction.'

Others may know more but I hear it's often triggered by  suspected fraud, or money laundering or to protect you from those things and to safeguard your money from criminals. Probably the bank doesn't know exactly what the issue is and the block is to get more information that it is a 'legitimate' business.

Barclays did the same to me a while back. A client paid by transfer, and after the booking when I logged in it said my account had been frozen and left a number to call. It was the number for the fraud department which really worried me. I spoke to a really nice women on the phone and she said they couldn't tell me why the bank had flagged my account as it against their policy as they don't want to alert fraudsters to what they look for regarding suspicious activities. She also said that I could withdraw cash from my local branch if it was from a salary if I had a wage slip and id whilst my account was investigated. I explained the situation, also the same client had transferred money to me previously with no issue so to this day I don't know what their reasoning was. I told them it was payment for a man's wax appointment block booking (I am a qualified beautician and this is what I pay tax for)
It took 5 days for them to unblock my account but it was very stressful in the meantime; I couldn't pay direct debits or anything and was terrified that I wouldn't be able to pay my car insurance, phone bills etc.
My advice would be to ring them every couple of days to try and hurry them along. They originally told me it would take up to 2 weeks but I kept on at them and it was sorted in 5 days.
Good luck!