If this is a big business, and it does not pay you on time regardless of the amount owed, this is a matter of principle.
I am not saying it is 100%, but if they owe you money and are not paying but generate a good amount of revenue, and you have not violated any of their TOS, and your product is legal then you can definitely seek a lawyer's advice and see what they have to say? If there is a chance of a settlement based on them not paying out then going through court the payout is probably not going to be $340, it will be a lot more.
This is similar to an employer holding your last paycheck and not paying on purpose. You could probably file a claim, or you could get more money. If there is a way to file a claim then you do not need a lawyer for that. If there is a chance of suing the company and getting more money then the lawyer will be on board and he/she will take his cut out of the settlement that you receive.
This is pretty standard practice in the US, I do not know about other countries. Logically there has to be a way to get your money without putting in much work.