If you are receiving similar speeds to the expected Chorus rates, this is likely the highest you will get. VDSL runs through copper cables, and speeds may vary depending on how far away you are from the nearest cabinet.
Environmental factors such as weather can impact performance as well. Chorus are constantly upgrading their VDSL network, and are also continuing to roll out Fibre which offers unmatched performance. If Fibre is available at your address, get in contact with us!
Chorus have more information on Copper here.
If you are still concerned, you can chat with us here: