Impossible to get in touch with the agent

Good afternoon, I have received a letter, mostly already notice to pay, saying I owe you some money as I didn't claim the Universal Credit, which I believe I am not entitled for and sorted it out ages ago with your agents. However, I am trying to get in touch for more than week with any of the agents but it is not possible. While I am typing this message I am waiting on the line already 55 minutes!!! This is ridiculous!!! The whole week I couldn't get of hold with any of the agents. It is any other way or number where I can get in touch with someone????? Being busy on the line it means 20 mins of wait not an hour! I am working person who doesn't have a time to wait my whole shift on the phone. Please advice

Hi,

Please can you confirm which department you are trying to contact? 

Thank you.