To Arriva UK bus companyOn 28th June 2023 I took the bus 509/510 from Stansted airport, departing approximately at 12:20, to the bus stop Hangar 10, 3 stops after Stansted airport. I was travelling in a group and my check-in bag accidentally remained on board. I tried to stop the driver, but he possibly did not notice me and the bus left. I immediately reported by phone the event to your company and I was invited to fill in a form on your website. So I did, including as well a full description of the bag and the content inside.It was a quite big check-in bag, impossible then not to notice it.Even if I was reassured by your personnel, I did not receive anymore any feedback, so my suitcase seems to be lost. This means that the bus was not properly checked or that someone stole my bag. I know that you have cameras on board. If this was stolen, this is a criminal offence I required then for the recordings to be analyzed in order to find out what happened and to understand who took it. I had inside items for a value of at least 700€.With this letter I am kindly asking you to refund me about my loss of about 700€.I am inviting you to refund me this amount as soon as practicable (if, of course, the bag won't be found). If I won't receive a feedback from your company within 15 days from the arrival of this letter, I will have to take legal action in order to protect my rights.Thank-you for your attention,Kind regards.Emanuele Barletta