GDK Drinks

I have tried for 3 weeks to speak to someone in HMRC and no one is answering the phone. Have held for over 30 minutes every time I phone so not sure what else I am expected to do?

I need to change from quarterly payments to monthly payments - have tried for 3 weeks to speak to someone in HMRC and waiting times over 30 minutes before giving up. Does anyone know how to either change this or how to contact the HMRC to speak to someone