I have a Joomla shopping cart component named "A" and at the same time have other component that was a forked version named "B", basically it was almost identical component
Here's what you need to do, the "B" have a payment plugin that the "A" currently don't have and the original developer seems to be too busy for my request, so, i ended here..
I will provide you with the copy of the "B" payment plugin where you need to refactor them back to be compatible with the "A" platform, it was super easy job since it was originated from the same extention, must be some prefixes changes was done somewhere and you need to revert them back, that's all, no from scratch coding, just altering some finished code works
I can integrate malaysian iPay88 payment gateway in your "A" joomla component. I will complete this work in a day.
Looking for your reply to start this work immediately.