These "features" are the whole reason you're building the app--so you can collect money (I assume). At my current company, we've spent the last four months rewr

These "features" are the whole reason you're building the app--so you can collect money (I assume). At my current company, we've spent the last four months rewriting just this part (moving to a different processor) and we're still not done. Our product lineup is not even very complicated, but working with payment processors is quite hellish. Considering this is the most important part of the application, this should always be considered ahead of time and plenty of time budgeted for it. There's no way you can try to speed this up and still implement it properly.