Had this a couple of times now with different things bought online, I'm not saying he is doing this (delaying) as I haven't dealt with Minh at all but, don't let it go over 45 days with PP or you have no course of redress.
If it was me I would ask the question outright to him and offer to delay any further action if he sorts it swiftly and within the 45 day period, if not he knows what you will do thereafter and it is then up to him