Another thought is - our son's a perfectionist and hates making mistakes so if I say 'say fan' and he says 'jan' and I say 'no, Fan' - that is the end of the world pretty much. He gets so upset. So I either say 'oooh that's pretty close, well done, FFan' or 'almost! Great job - you said FFFFFan' - so he's encouraged but I also demonstrate how to say it properly again. Or if you want him to say it again, perhaps you can say 'ohh that was great, can you show Dad how you say xxx'? That might work, and help your son feel like he's doing well and getting it right.