Amazon India — complaint against amazon delivery agency. order #[protected]

Address:

Andheri West, Mhada, Mumbai City, Maharashtra, 400053

I had order Wall sticker 'tree', vinyl 49cm*4cm*4cm on 30/07/2019
Order #[protected]
Order total- Rs 219.
Instead of Rs 219 amazon delivery boy has taken 750 rupees from my old mom, as she was not aware of my ordered good cost.
On the next day i Immediately call amazon customer care executive they given us assurity, after investigation that difference amount will transfer within 7 days.
Till today i have called many times to customer care they have prompt reply" Sir investigation is going on"
Even i contact to local amazon delivery agency, the guy said " Sir we doesn't get any revert from Amazon".

It's almost 80 days passed away, still haven't received any update.