After opening an account, wagering and winning account closed with no further information given

I opened an account on the 17/6/18
I deposited 2300 pounds over several hours and played with no issue.i put through a withdrawl request for 2700 pounds and sent all documents requested.i was then told today that my account had been closed because i previously self excluded from another site associated with themselfs.i am not aware of this and they will give me no further information.i was also told instead of receiving my winning i will only have my deposits refunded.