This occurs due to the fact that the primary card gateway (used on the option "Credit / Debit Card") only supports transactions above 1.00 GBP (roughly 1.20 USD or 10 RMB). In order to correct this, please load a higher amount to the account credit (which you can then deduct to any pending payments), execute a bank transfer, do a crypto payment, or use the Stripe Gateway for payments.
Thank you for your understanding.