Sorry you getting so much flack here OP.
My mum was accused of shoplifting when I was about 8, in the early 1970s. It was a packed store and miscommunication between the person who served her and knew she had paid, and the other worker who saw her pick up the item (a can of drink) and walk out. My memory of it is sketchy, but there was loud yelling from the shopkeeper in front of a lot of people. I'm guessing it only took minutes to sort it out, but mum was humiliated and refused to set foot in the store again. She was also embarrassed and worried about word spreading. It was long before social media and cancel culture, but she very definitely never forgot it.
When she passed away in 2019, I had the task of clearing out her place. She had kept every single receipt she had ever been given in the 34 years she lived in that home. I also take a receipt for all purchases, but I throw them away within a few days, unless it's a major purchase and related to the warrantee. I hope you can move on soon and get back to a more regular way of shopping.
As for the guy harassing you since, it has been a month, so not like we are talking multiple people a week. I hope you told him to sod off. I get that it must be unsettling though, but on the whole, people do move on pretty quickly. I would hope that this wouldn't happen again, but maybe you would feel a bit better, if you had something written to had anyone who approached you again. I asked Chat GPT what to write.
I know that some here will probably say this is equally crazy, but if it makes you feel better to have a couple printed and in your bag, then do it.
Apart from that, do try to let it go. I know it must have felt awful, but you have to find a way to move past it. Wishing you well.
To Whom It May Concern,
I am writing to formally state that I was recently and falsely accused of shoplifting at WHSmith. This allegation has been fully investigated and disproven, and I have been cleared of any wrongdoing.
Despite this, false and defamatory claims were circulated on social media, and I have since been subjected to harassment and verbal abuse in public by individuals acting on this misinformation.
Let me be absolutely clear: any further harassment, defamation of character, or disparaging remarks made about me — whether in person, online, or otherwise — will be treated as a criminal and civil matter. I will not hesitate to pursue action under the Protection from Harassment Act 1997, the Defamation Act 2013, and any other applicable UK laws.
This is a final warning. Continued abuse or spreading of false information will result in immediate legal proceedings.
[Full Name]
[Optional: Date or contact information]
Obviously you don't have to add your name, but it may make the odd nutter think twice if it gets that far.