Your application is not complete/submitted until you pay for the visa application.
So, if it’s giving you trouble, I’d start a new application all together.
However, do you have all your documents in your hands, completely ready to submit to Sheffield, including a wet signature letter from your landlord? You should not submit the online application until you are completely ready to post the documents, as the date you pay for the visa is the official application date.
Sent from my iPhone using Tapatalk