dial 150 or 0345 454 1111 and follow the prompts to - 'thinking of leaving us' - then "technical issues" - dont worry about that they do much more - open 8am -10pm 7 days a week - should take you to a UK call centre
Thanks for your post and welcome to the forums. It's great having you on board with us although we are sorry to hear that you're having this issue.
The teams have been a little busier than usual however they are working as hard as they can to get to you.
Try giving them a call during the day as wait times seem to be lower
Let us know how you get on.