Held my money for 6 weeks. Still waiting.

My ex partner opened this account for me.cashplus pre paid card. I had bad credit so my tax credit went into his account. He withdrew the money and gave me it. We never had a problem with this. His account has now been suspended. Leaving my tax credit money stuck in his account. They want proof of his claim with DWP. He doesn't claim a penny. He works. They want proof of his nat ins. Why ???? I have sent proof of my nat ins no to them. If they look at the payee reference is my name my national insurance. In 6 weeks not 1 person has had the decency to return a call he has made. They're refusing to unblock the account. It's my money. From DWP. Surely this isn't allowed ???
I've now changed my bank and won't have a single penny paid into it. My ex wants to close it and give me the funds.
I've gone to obmusman but because it's his account he has to do the complaint. I'm livid. This bank left me and my boys 3&4 with no money over Christmas. They need reporting to higher people. They should not be allowed to do this. Shocking bank !! STAY AWAY !!!