I'm assuming that the account being deactivated means that OP can no longer access historical statements, but could OP not ask their TA for a list of transactions that the TA carried out on their account? A responsible TA would surely have logged all their activities and OP could then ascertain whether their TA did anything to contravene the T&Cs.

It seems that OP has placed and is continuing to place a lot of blind trust in their TA, who after a cursory Google search, is actually an independent contractor who works with - not for - the agency,