I am sure they don't want to lose you as a customer. You might want to contact their Customer Service manager and explain that you've been happy with them so far, but it looks like your needs are not being met by the $4.95 plan. Explain what your needs are (and remember that nothing in shared web hosting is truly unlimited). Chances are that they will want to keep you happy and will work with you to find the best solution with the products/services that they offer. You might be better suited with a managed VPS.