Member Info for Robdbank

Good morning all.
Does anyone here have any information on the following please?
I have a non discretionary account with a stock broker. Yesterday, I discovered that, back in February, they liquidated some positions in stocks I held as my exposure had exceeded what was acceptable to the custodian. No one contacted me regarding this situation and the broker liquidated stocks at his own discretion.
The problem now is that he sold 75% of my holding in a stock that has trebled in value since selling.
Question is, did he, or the custodian, have any obligation to inform me of my accounts position and the subsequent decisions taken to get the account back in shape? I have other accounts that tell me if I need to fund or liquidate before taking action.
This doesn't seem right to me, but I'm unsure to my rights and their obligations before acting.

Thanks in advance.