First, how did you purchase the gold? Direct purchase, or you top up your account with RM500 first before purchasing using your HG wallet? Purchase/Top up using Boost or not? If any modes other than Boost, you will have surcharge as stated in HG FAQS here: https://help.hellogold.com/en/top-up-processing-fee/

Second, don't forget you have a 2% processing fee, even at the stage of purchasing your gold. So you already received less than RM500 worth of gold.

Third, there's another 2% processing fee for selling your gold. So that reduces it even further.

But one thing that I'm surprised is that you only received 2.679g of gold when you purchased RM500 worth at 168.7/g. By my calculations, assuming there's only 2% processing fee (without RM1.20 top up fee) you should be getting like 2.8g+ or something. Perhaps we need some other sifus to explain how to calculate conversion of RM500 to gold 
1 night only, the storage fee or administrative fee is practically non-existent lah since it's 2% per annum only