They either installed the wrong bearings and/or over tightened the bearing cups. Either way it is accelerating the wear of the bottom bracket assembly. You need to go to a different shop, better yet perform the service yourself, it isn't that difficult and the tools will pay for themselves in two services. I would suggest you Email Dawes and find out what the orginal bottom bracket specifications are for your frame model and chainwheel set. Then order the part or it's equivlent yourself
Here are the instructions for replacing and adjusting cup and spindle bottom brackets