An Opencart Expert who can implement Google Suggestions

We need an opencart expert who can go through the whole-set of feedbacks that Google has provided and implement these with precision. Right now, we are not able to run one set of our ad words because one of the page is throwing back an error. Here is detailed feedback from Google: I understand that you are concerned about ads disapproval in your AdWords account #815-777-7959. Appreciate your efforts in making changes to your website! We have re-reviewed your website and unfortunately your website is still returning invalid HTTP response. How to fix this issue? I would request please consult the Crawl Errors page of Search Console (also known as Webmaster Tools) to troubleshoot and resolve the issue. I would request you to refer our help article more information on how to use Webmaster Tools to troubleshoot crawl errors. Also, please use below HTTP header tools or share with your web developer which will help you in fixing the error. [login to view URL] Please make the necessary changes to the website and reply to this email. So that, I will be able to review the website again and Once the website will comply with all the Google policies and approve the ads.