Hi! Could I see the website please? There may be a number of issues going on, I'd like to take a look and try to work out what I think it might be. We had a similar issues a few times with the yacht site and overcame it each time, always different reasons.
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British living in Manila - Website Applications Developer - PHP/MySQL / HTML/CSS/JQuery/AJAX/JS / SEO - 11 years experience building front-end and back-end for a global yacht charter company. I was the sole developer for 90% of that time. I also built my own online yahtzee (dice game) community with real-time games/chat which is still fairly popular today.
Some of the projects I have completed: booking systems, search/sales/accounts/management/CMS tools, file upload handling, image processing (sizes, adding text, grafting two images etc etc), on-the-fly PDF creation, automated emails with files attached, web-scraping (with/without login spoofing), email scraping, financial/accounts calculations/reports, complex management reporting, proposal creator, editing responsive designs, real-time chat and AJAX-based games, community forum, paypal API, google maps, calculators, etc etc.