British Airways complaint: Miss sold upgrade

The day before travelling from Tolouse to London I was offered the option to upgrade from Economy to Business Class. As I had a lot of work to do the morning I was travelling I decided to take up the offer, based on what I was advised I would receive. The offer stated that by upgrading I would received priority check in, use of the lounge at the airport, Priority boarding, fine dining on china plates, and priority baggage. I was not given any of theses things. I was given a sandwhich in a bag and offered a drink on the plane but the rest was none exsitant. At Tolouse the check in opened late and the actually opened the Economy desk before the Business class desk. The person checking in was not particuarly friendly and did not provide me with any updated on my flight. When I went to use the lounge along with other business class travellers, I found the lounge shut. There had been no mention of this at check in and I had to find a member of airport staff to clarity this. I was then advised that it was just shut due to covid, although other food outlets were open!. I was last to board due to changes in boarding due to Covid. Although I understand this, I feel that this should have been taken off the BA offer. On the flight I was indeed offered a sandwhich and drink, but not what was advertised. On collecting my luggage my bags came through as one of the last bags to be delivered, holding me up further for my meeting. I have complained to BA who have advised that although I did not received what was advertised, because I actually sat in the Business class seat, then they are not willing to refund the upgrade fee. I had not asked for compensation for my inconvenience at not being able to complete my work prior to travel just for the additional upgrade amount I paid.