My name is frequently mis-spelled. (So is my surname, funnily enough). That doesn’t really bother me, except that if, once I’ve corrected them, they still insist on using the incorrect spelling, then I get a bit irritated. If it’s people I’m unlikely to encounter again, I let it pass.
My first name can’t really be shortened, but on occasion, in the dim and distant past, some tried to lengthen it, thinking my actual name was a shortened derivative (which it isn’t), and I must admit, that annoyed me at the time, (especially as I really dislike that longer name) and I was quite indignant that the lengthened version they thought was right was most definitely not, and would they stop using it, which they eventually complied with, I’m pleased to say.
I suppose, in the grand scheme of things, getting upset about how your name is shortened, lengthened or totally mis-spelled is perhaps over the top, but actually, most of us probably like our names and hope that other people will be respectful enough to use the name we wish to be known by and spell it correctly once its correct spelling is pointed out.