When did you pay for it, and for how long? I think this sort of thing can happen if you don't renew on time, companies like this are waiting to snatch them up. That may not be what's happened here, but I guess just check and sure that the domain name registration (not just the webhosting service) was paid for.
You might check out this site for info on how to dispute domain ownership and unauthorized transfers. The first thing it says is to try to resolve it with your original registrar, who may or may not be your web hosting service as well. They would be the ones who should have record of exactly when the transfer occurred and may be able to resolve it, if you can figure out how to get them to respond.
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I read some online reviews of DB Multimedia (lots of negative reviews), but one thing I saw is that you have to submit a "trouble ticket" to get any kind of response from them.
Whether or not you get your domain back, I'd suggest transferring to or registering a new domain with a first tier registrar like godaddy.com and get your webhosting from a different company.
I made that switch recently and have been happy with it. When I initiated the domain transfer request online, Godaddy actually called me that evening to make sure I understood the transfer request, and were very helpful and friendly.
For a webhost I picked hostpc.com after reading favorable reviews. I had a minor issue when I was first setting up my site. I submitted a trouble ticket and it was taken care of within five minutes.
Hope that helps.