Lidl complaint: rasist behaviour, discrimination

Came to the shop Thursday 18.03.21 between 13:30 and 14:00. Can’t wear a mask as I’m medically exempt. As I came to the till I let a gentleman I know to go first as he was only paying for one thing. Member of staff heard me taking foreign language to him. The lady serving didn’t have a mask on. While I was packing my shopping she pointed at me and called security guard, she didn’t say a word to me at this point. He came and asked why I don’t have a mask (I’ve seen at least 3 people in without them, nobody bothered). I politely explained that I am exempt. He told me to bring a proof from my GP next time and threatened he won’t let me into the shop. I said that he can’t ask me about these things as it’s in breach with government policy. He said that he doesn’t care as Lidl allowed him to ask and he is within his rights to do so. The lady at the till backed him up (not wearing a mask herself) and said anybody can say they are exempt and Tesco won’t let me into the shop either. At this point I asked to speak to a manager. After a bit of a confusion as they were trying to figure out between them who to call a lady came in and said that she is not interested in Government procedure (at this point I had Government website opened)as Lidl procedure is not to let people in without a proof of exemption. I told them that breach of this procedure may lead in a £1000 fine for a person who demands proof of exemption. At this point security guy try to intimidate me with an information that I can be fined few hundred pounds fine if I don’t comply. Manager said that there is nothing else to ”talk about” and left me with no help. I packed my shopping and all shaken and stressed left the shop. On a way out I asked security guard about his name (as he escorted me out) but he said he won’t give me one as he doesn’t see the need (but quite happy to demand my personal medical record). Leaving the shop I felt humiliated (as towards the end of a conversation the unhappy queue of customers raised up to 6-7 people. Considering that nobody else without a mask was treated this way I’m lead to believe my foreign nationality played a key factor in being stopped and shamed by 3 members of your staff.