Search Engine Rating


I wondered if anyone might be able to shine some light on the fact that my statistics, that is my site visits have taken a massive nose dive in the last 2 months and that google now lists my site on page 5 rather then page 1 as it used to. I've just had my site SEO by CS-cart market place but 5 days later my stats are still sooo bad. I'm not technical so can't sort out this stuff alone. What could it be? Thank you in advance.

BTW I was advised to block a few bots a while ago at they were coming in and out of my site as if they were jammed and using up all the memory on the server. I unblocked them about 2 weeks ago but things are worse if anything.