Fix Bug in Mijoshop - (Joomla & Opencart)

I have a website in Joomla 3.6.5 and Mijoshop 3.1.5 (Opencart 2.0.1.1 integration) I have a problem with the checkout which the Mijoshop author refuses to fix. I need someone to fix it. The problem is as below: If you add something in the cart and try to checkout through registering a new account and not as a guest, you follow Opencart checkout steps 1-5 where the system fails to detect all the payment options available. If you press continue to step 6, the page reloads, you are being logged in and redirected to back to step 2. Then if you continue to to step 5 again, the payment options are all there as they should, and you can continue to complete the order successfuly. If you checkout as a guest, everything works as intended. All shipping and payment options are there and you continue seamlesly from step 1 to step 6 with no problem. The normal checkout procedure of Opencart is like this: 1. You chose to register avvount 2. You continue to step 6 with no interruptions 3. You complete order 4. You are automaticaly logged in. The problematic Mijoshop checkout is like this: 1. You chose to register account 2. You continue to step 5 (where the system does not show all the available payment options) 3. You are logged in and redirected to step 2 4. You continue to step 5 (where all the payment options are there) 5. You complete the order. Who can fix this? Please give me your offers.