Cookies Problem?

Hello all. I would like some help cause i cant make it. Cs Version 4.3.4 .

Have an addon installed for payments and works perfect. Installed an addon for analytics and works perfect too but has one big problem. When we use chrome browser ONLY and make a payment with credit card unfortunately the return url changes to Https://my-domain.gr/login/?return_url=index.php?dispatch=checkout.complete&order_id=instead of Https://my-domain.gr/index.php?dispatch=checkout.complete&order_id=!!! so we cant have the results we want sent.

If we clear cache-cookies from chrome then everything is ok and the return url is normal.

If we try to do a second payment with no cache -cookies cleared the error appears again.

Is it something with cookies? with sessions?

Help plz