First off I tried taking my iPod Classic into a Mobile Booth store. They agreed to replace the battery but then kept it for over a week with no communication. When I chased it up they finally returned it (with a big new scratch on the front) saying they tried their best but couldn't do anything.
Should have sent it to iPodDoctor in the first place. They sent it back to me after just a couple of working days, all the while updating the status of the job, so I knew it was in safe hands. Received it yesterday, extremely well packaged, good as new with a battery that works as well as when I first bought it. Would recommend and definitely use again. Thanks!