No, you're right, it is annoying. I happily mix with a wide variety of accents and pronounciations and few quirks annoy me but ding-ee is one of them.
The other one is how some people oddly extend the vowels in 'Kenya' to make it 'Keen-yah'. Presumably if they met a chap named 'Ken' they would mis-pronounce his name 'Keen'!
Makes no sense at all, and one of the reasons Welsh is such a wonderful language.....learn a few rules, and you can pronounce any place name! <g> Honestly!