Hope this helps. This is what i get from CS :

During the temporary 7days Mnp plan :

-The call charges is still the same, there is RM0.15 per minute, RM0.10 per sms and the data services we give you for 500MB.
-This temporary plan have a expiry date for 7 days, so we giving you free 500MB data usage within the 7 days
what did they tell u ?

It's different if the shop refuses to accept your MNP though I can't imagine why, but I don't think this is the issue. Unless I'm reading it wrong, they clearly want his port to be successful before accepting payment and issuing the iPhone. For customers in this predicament, it's best to pay up all outstanding bills so that the port will go through in as short a time as possible.

Regarding paying up front, are you paying RM 2,090 / RM 2,490 in cash? If it's by credit card, what if the port is unsuccessful? The amount has already been charged. Assuming you are cash rich and pay up in $50 ringgit bills, would you as a retail store owner accept that much cash from a person who may or may not be your customer? What if he comes back and claims he gave you more? What if you lose it?

I really seems pretty straight forward and easy to understand if you ask me. I'm not the easiest customer to deal with myself but I am able to come to terms with things that make sense and this makes sense to me.