If you can't make a new request, it is likely because your current balance has gone below the minimum! Click on your icon and find settings from the dropdown. You will be able to see billing with your current balance and pending transactions. Check if your balance minus the pending amount is over your minimum balance. You must have a minimum balance on your account after the pending amount in order to make a new request.
If it is over your minimum balance and you are unable to make a request, please contact your account manager.
If you have further questions about how billing works, check out our 'How does billing work?' article!