I cancelled a reservation via the booking.com mobile app, which the app confirmed and updated by removing from my upcoming visits on the app website, so I took this as cancelled. It wasn't until I received the full charge for a no show reservation that it was brought to my attention that the booking.com app had not cancelled my reservation. After contacting the hotel and booking.com they both refused to refund even though it was their systems error. I had received no confirmation email so had no proof to provide. I asked to make a complaint but was advised my complaint was 'not a valid complaint', but of course they were 'sorry for any inconvenience caused'. I had always used booking.com but after this experience I would not trust their systems or their customer service. I would never use again or recommend.