Unfortunately the RingGo parking service do not maintain the on-site payment machines. All machine faults should be reported direct to the parking operator as it they who own the machines (their contact details should be displayed on local signage and/or tariff boards). This includes when you use a credit card in the machine and it doesn't provide you with a paper ticket to display in your vehicle.
If this happens you can still pay for your parking with the RingGo parking service by calling our automated payment line on 020 3046 0010, (or 020 7125 9090 in Westminster) or via our mobile apps or online (including our mobile site) at RingGo to avoid the potential issue of a parking fine. You should then apply for a refund with the parking operator direct for any coins lost in the machine or to establish whether your card payment was successful.