Looks like you got in contact with our Support team after this was posted, but I wanted to respond here too. I'm sorry that you have been having trouble with your open rate. Your success is very important to us. I looked in your account and I think your emails look great. They are definitely well aligned with current best practices. Here is also a link to our "Email Best Practices" FAQ, which may have some additional tips. In addition, one of the most important things to consider when looking to boost your open rate, is a strong subject line. Here are some tips for creating strong subject lines.
I also noticed that you have our Email Plus package, which gives you access to our Survey tool. Creating a survey is also a great way to boost your open rate. With a survey you can ask questions to gather ideas of things your customers are interested in hearing about, which can help you tailor your emails to be geared towards certain interests.
Additionally, if you are looking for more feedback on your emails. We have a great forum called "Critique My Campaign" right here in the Community, where you can post your email and get feedback from other customers. I hope this helps.