shopping cart having problem with https

I have a site www.afrosho.com where i use the shopping cart funtion.
When shoppers want to check out and fill thier delivery information, the site displays the message:

Could not connect to remote server

Check that the address is spelled correctly, or try searching for the site
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afrisho.com/index.php/homepage-2/cart

I observed the address changes from http to https and therefore stops furhter processing

Please what is the problem and how can resolve it
thanks

Link you sent us does not work.

you dont understand what i mean.
when you add a product to the cart and want to check out it will lead you to the link i gave and the link will not work or is not working

If that is old vm < 2 , maybe virtuemart.cfg.php is not configured for new address. Open it and if you see that address some-ware in content replace it with your actual address