Thomann Acoustic-Bass Jumbo Gigbag

I ordered a Harley Benton B30 acoustic bass, and at the same time I wanted a gigbag for it. It is a low budget instrument, so I didn't want to spend much money on a case or an expensive gig bag, so I decided to buy a Thomann low budget acoustic bass gigbag. When I ordered the goods, I put a standard size gig bag to my basket, but then I noticed that there is a Jumbo version of that, I changed my mind and bought that as HB B30 is supposed to have a jumbo style body. After having unboxed the delivery I realized that this gigbag is far too big for the bass. Why is it designed so? I don't think other acoustic basses are much bigger. This is inconvenient, clumsy and does not protect the instrument well, because it is moving in the bag.
The straps are attached too low, so the gig bag reaches too high, that's why it's a big risk to carry it on your back. The other handle is too far back (towards the bridge), so when you carry the bag it becomes imbalanced and the head starts to dive. The handle should be sewn just about 20 cm nearer the neck. The back straps should be sewn higher, or they should be more adjustable.
The quality seems to be good for the price so far. The size and the design are incomprehensible for me. Even the guys who designed the cardboard box the guitar came in had more idea about how big an acoustic bass is.