I haven't heard of Magin personally, so can't comment on that one in particular. However, it is quite coming for new accounts to have some trading restrictions attached to them from merchant gateways to protect themselves
What can usually help is to give the payment gateway as much information about you up front as is possible. Let them know what your trading intentions are, the amount of money you expect to be going through your account and so on. It's all about building a relationship with them before you have the need to.
I'm not saying that will work every time, but you might be surprised at just how well being proactive in these types of matters really helps a situation.
Most people don't worry about doing that, they charge head long into a nightmare and then wonder why they get the hammer dropped on them and when trying to then resolve the situation, the merchant not playing the game they want them to play.
The safest option for new accounts, start with a few very small sales that you have the funds to cover up front yourself. Then ensure you get tracking information provided to the merchant asap to grease the wheels. Then slowly move up in value so you don't scare the merchant and it throws a red flag from out of no where.
Use that strategy, along with good upfront open communication with them and you're putting yourself in the best possible position NOT to have any major drama with extended account holds.