If your bottle of Dunglass states it's a pure malt whisky - this means it was blended with other malts from different distilleries. Pure malt is the same as a 'vatted malt'. A pure or vatted malt does NOT contain a combination of malt & grains from different distilleries - those produced this way is a blended whisky.
A single malt is produced by a single distillery. If your Dunglass is a single malt, it would (should) certainly state so.
Can you post a photo of your Dunglass?