It happens to everyone at one stage or another. Where I live, and where I grew up, my surname is extremely rare, in another part it's a different matter, and also a different point. The problem is, is that a lot of people misspell it, a lot. The worst ones are my bills, even though I have on several occassions spelled out my surname to the customer services department, in a loud, clear manner, I will still recieve a bill with my surname spelled incorrectly. Yeah, it might seem funny, but I have on two occassions recieved, shall we say, threatening letters from my old phoneline provider, saying I hadn't paid my bills for three months, all because they had my name spelled incorrectly. After proving the first time that I had paid my bills, I chalked it up to a simple mistake, and they promised to fix it. Naturally, the second time proved they hadn't and I was threatened with having my phoneline cut, so I switched.
Like I said, it might seem funny, but it can be a problem for some people. For me, it was just one letter being changed for another and another being added onto the end, thats not much. But yes, I will agree with Akima on the point that if someone keeps making the same mistake, despite the fact that you have told them several times the proper way to pronounce it, then yes, they are being disrespectful, and they themselves should be treated the same way.