S H O C K E D ! Paying with debit card has a price

I needed some cash... so as usual I went to my humble money spurting machine ( it starts giving you less as the month ends :D) and as usual with the tit tit tit tidit tit... and when I saw my balance

I WAS SHOCKED

Panicking....My mind when about searching my memory box... and my inner soul screaming at my impulsive spending disorder... I was like... hey.. I didnt spend that much at all...  an astonishing level of RM400 was missing from my account ... (thinking..thinking..panicking..) .. so i tit tit tit tidit again... to check my transactions .. and it shows somehow on the 21st I have made some transaction twice amounting RM200 each...
but I didnt even buy anything... I'm on saving mode.... :(
so ... what happened...

Whatever that may be.. Maybank has a cool customer service... They have thus far not let me down yet.. so I made a quick call .. explained my situation in my utterly calm yet drama queen tone.. and after some questions and answers....

The sweet CS exec asked...

Did you pour petrol by swipping your debit card at any petrol station .. i.e Shell or Petronas...!!!!!!

ok I blinked for a moment there.. and went.. yea.. I did.. twice on Sunday (21st)

and thats when the truth came

It seems petrol station take a pre-authorised debit of rm200 each time your pour petrol via swipping at the pump machine... so twice is rm400
and this only happens at either Shell or Petronas..
and after a few working days.. the money will be credited into your account after deducting the amount poured...

So I was adviced - to pay at the counter / swipe at the counter rather then the machine...

Well a relieve it was... but no matter what I am still RM400 shorter for a few days.. sobs....