Beware this is a total rip off
I went into London and spent two hours trying to pay the £12.50 charge that evening. I finally got one receipt via text on my phone but latter discovered they had taken the payment twice. You cannot get your money back and the the Chat on TFL sends you to a web site called Expert Squad this company is a subscription company that will take every penny out of your account . It is owned by another company TSFF Holdings Ltd and is based in Cypress. The banks should block them and the Financial Ombudsman should investigate them for corruption and being listed on a government web site.