Hi @Kaylz - you need to be up sharp to call O2 with a chance of getting through, around 08:15 UK time in the morning seems to work best to get onto the proper Muzak queue and not get cut-off unceremoniously.
All the numbers in here if you need'em: Guide: Coronavirus Community Help and Support
You can also call customer service on the 0800 number using Skype, a tutorial here if you want to try it. It's good for video chats too! https://www.digitaltrends.com/computing/how-to-use-skype/
Track usage, upgrade and get support with the My O2 appDownload My O2