Peugeot 306 rear brake seize!

I have a 1997 306 and yesterday the rear brakes seized as I was going at 10 mph. The AA guy said it was common on the 306. He 'fixed' it with a big hammer and several blows to the drum. Before I take it in to Peugeot has anyone else had this problem and if so, what was it? The rear brakes are drum brakes and I cannot get these off because I do not have a puller.