Trip.com complaint: Travel credit

I booked a flight via Trip.com – Alicante-Dubai, British Airways (business class). As the omicron variant began to take hold around the world, I called Trip.com to share my concerns about travelling as my husband is living with cancer and therefore immune-compromised. I was advised by Trip.com that I could cancel my travel and be issued with flight credit to be used for future travel. I received email ation that the flight credit was available to use by 31 August 2022. I am now trying to re-book the travel and being told by Trip.com that due to changes in fare rules I cannot use my flight credit. On British Airways webpage, it clearly states that flight credit can be used up to 30th September 2023. I have contacted the Customer Service of Trip.com who agree that the credit voucher is valid but when it comes to re-book, it is declined – I have tried three times. I now feel that I have been given mis-information, inaccurate advice and mistruths.