Formal Complaint Regarding Misleading Promotion and Service Experience - Billy G Montecasino

I am writing to formally raise a complaint regarding my recent experience with Billy G on 13 February. I made an online reservation on 9 February for 12 February. On 11 February, I received a confirmation call during which I enquired about the 30% promotion and was advised that it would remain valid until 13 February. Based on this information, I requested that my booking be moved to 13 February, which was confirmed. On 12 February, I received a further confirmation call and again specifically asked whether the promotion was still valid. I was once more assured that it was. However, upon arrival at the payment station on 13 February, to my shock was informed that the promotion was no longer valid and was told that the back office"doesnt know anything" I felt embarrassed, frustrated and forced to pay more than i had planned, simply to avoid causing a scene. In order to avoid inconvenience to other customers behind me, I proceeded to settle the full amount(WHICH I STRONGLY FEEL ITS UNFAIR) I thereafter requested to speak to the manager on duty inside the restaurant. Unfortunately, the matter was dismissed with no attempt to investigate or provide a resolution, and I was simply informed that nothing could be done.'SORRY' I find this extremely concerning, as my decision to proceed with the booking was based solely on information provided by your staff. This resulted in me paying more than anticipated, which I would not have agreed to had accurate information been given. I respectfully request that this matter be reviewed and that appropriate feedback be provided. I believe customers should be able to rely on information given by your representatives. I look forward to your response.