Justin Bieber Launches Drew House Collection 2 Despite Delivery Issues

Justin Bieber's clothing line seems to believe the ol' saying, "Always leave them wanting more" ... because his second collection just launched, while some fans wait for the first to deliver.

Several Drew House customers tell TMZ ... they haven't received their orders from the enormously popular brand's Collection 1, which launched on January 29. It was such a hit, it sold out in a day. They say they were told the products would be shipped out in 5-7 business days, but more than a month later, it hasn't happened.

We're told Bieber's company contacted the customers about the delay -- blaming it on "overselling" -- and even offered refunds to folks who don't want to keep waiting. Otherwise, they've been promised the items will be restocked next week and delivered asap.

The hiccups don't seem to be affecting the recent launch of Collection 2 -- which includes more shirts, pants, sweats and hats but in different styles -- because 4 of the 12 new items are already sold out.