I have a Google Pixel 5 (imported from the USA) that supports 5G Sub6 , however, I cannot use the 5G in NZ for some reason. VoLTE is all activated, I am not using dual-SIM

MODEL NUMBER: GA01316-US

Is totally unlocked to work in New Zealand

I went in-store to try and have it activated, it was all good on their end however still on LTE, not 5G. The guy at the store said: "the Pixel will only turn on 5G when it needs it - such as watching 4K video" - don't think that is true. 

Checked the bands and it does support the 5G N78 band that Spark use.

Any ideas? thanks