Chat waiting time feedback

We have a Live Chat services but the problem is we don't have enough number of agents to answer all the inquiries of all customers. So customers really need to wait especially during peak hours.

Our initial solution is to show the Queue number and the estimated waiting time but at the moment, we can't implement it due to technical limitations.

Do you guys have any suggestion on how we can improve our Live Chat experience for customers waiting? What do you think is the proper message to tell to the customers that they need to wait in a way that they will understand the situation and they will not be frustrated. Thanks!