Should I be getting 4G on this dual SIM handset?

[Koofler]

I've just got a dual SIM Samsung S6+ Edge form here http://goo.gl/VEOXKM and it all works so far except getting a 4G connection on the primary SIM. It seems to only get H+ at best. I checked the spec with my (useless) O2 reseller before I bought it and they said it would be ok. I've swapped the SIM into another UK spec S6 and it gets 4G fine.

Does anyone know where I'm going wrong? I have updated the APN settings both online & manually but so far without any luck.

[Koofler]

The bands listed on the spec sheet are:

4G FDD LTE B1(2100), B2(1900), B3(1800), B4(AWS), B5(850), B7(2600), B8(900), B12(700), B17(700), B18(800), B19(800), B25(1900), B26(800), B28(700)
4G TDD LTE B38(2600), B39(1900), B40(2300), B41(2500)

AFAIK O2 are 800Mhz which seems to be B18, B19 & B26 - not that I've a clue what that means!

According to GSM Arena:

NETWORK Technology
GSM / HSPA / LTE
2G bands GSM 850 / 900 / 1800 / 1900
3G bands HSDPA 850 / 900 / 1900 / 2100
4G bands LTE
Speed HSPA 42.2/5.76 Mbps, LTE
GPRS Yes
EDGE Yes

Edited by Koofler on Monday 12th October 14:27