My understanding is that Mycash is not reversible, especially if I buy using cash.
Most people around here stay away from mycash now. To many carders buying and selling them,
some will go as far as saying they are cash bought and provide fake receipts. They've gotten good it at and it's hard to tell the difference unless you know what to look for.
Assuming you are the one buying these cards and not just reselling, you're better off buying BTC through cash deposits at banks. You'll get more BTC that way too since you can drop the markup and still find sellers. WU and MG would be another option, drop the markup to cover the fees and you're good. Once you build up enough trust here you'll find it much easier to buy using other methods.