Hello there,
I have gone through you project details, I can surely help you in creating Prestashop module which will be integrated with inter-switch web pay API.
We are a 10 year old IT company with highly skilled designers and developers to work on php, Mysql, Jquery, Wordpress, OSC, Magento, Prestashop, OpenCart, Mobile development, iPhone, Responsive etc.
It would be better if you come to have a close discussion over chat .
Best Regards
Harpreet Singh