Hello Toots and Happy New Year!
First of all, Japanese people tend to pronounce English in their own way (like people from other country, by the way, we're all influenced by our mother tongue). As for "San Kyuu", the sound [k] being attached with the sound [yu], there is also another reason: it's because of the reading of the numbers 3 (san) and 9 (kyuu). A few years ago, people would write "39" (san kyuu) to say "Thank you".
I hope this answer your question!