I inquired and answered my own question
Can you describe what it is you're trying to do, I honestly cannot follow your question? What is an "MS avenue"?
The maximum stored value on a Rabbit card is 4,000 baht. Stored value can be used for fares, and for purchases at dozens of participating merchants.
They stopped accepting credit and debit cards for stored-value top-ups ~ 2 years ago. I think you can still add "trips" to a Rabbit card via a credit and/or debit card.
There is the Rabbit - LINE Pay option, which does allow one to add value via a linked credit or debit card, and then spend that stored value on BTS fares and at merchants.
I am not aware of any options of recovering stored value in the form of cash.