#4000 have been removed from my bank account instead of #2000

Hi Adewale, if you were overcharged for a transaction, you need to contact your point of purchase. If the transaction was done via your bank app or USSD, you need to contact your bank for reversal.
If the transaction was done via MyMTN app or MTN OnDemand *904#, you need to contact MTN support for resolution.
You can contact MTN support via any of these channels:
1. MyMTN App
2. Facebook: @MTNLoaded
3. Instagram: @MTNNG
4. Live Chat: http://bit.ly/2OC5bHz
5. Email: customercareng@mtn.com
6 .WhatsApp: 09033000001