"Twitter CS say i cancel through call , FB CS say i cancel through their help center."

Call = Help center.

The customer representatives are only stating what they saw on their system log.
If you really did not call to cancel, it means their system got bug liao.
An auto order cancel bug huh... That sounds like a disaster to the business.

I hope you can make them refund.
Support you to do what is right. It's not about the rm20.

Tell them
>you did not call to cancel.
>tell them it's potential system bug.
>ask them to initial an investigation.
>ask them to escalate to their TL or manager.
>tell them AGAIN not to close the case without consulting TL or manager.

If they did nothing internally you can only resolve it with outside inference
>something like consumer tribunal to get back money.
>something like social media for some form of social justice.