Expansion, Refunds and Upgrades
Yes, you can upgrade to Deluxe. There is an item in the gem store, similar to the original Deluxe Edition upgrade. It costs 2400 gems. The upgrade contains everything included in Ultimate except the discounted gems, which they are under no obligation to offer.
http://wiki.guildwars2.com/wiki/Guild_Wars_2:_Heart_of_Thorns%E2%80%94Digital_Deluxe_Upgrade
(edited by Trise.2865)
You can not upgrade to Ultimate from either the Standard or Deluxe Edition. This was clearly stated when first announced. What the CS Team has done, in the past, is refund the Standard Edition, and then you can purchase the Ultimate Edition.
You would need to contact the Billing CS Team and discuss the issue with them via the ‘Support’ link above/below and ‘Submit a Request’.
Good luck.
Just be careful in your wording of the refund, to make sure they understand you do not want to lock your account. Which is what normally happens when you ask for a refund.
Arenanet is very good about refunding and when you state clearly your only wanting to get refunded for the HoT expansion there is no reason they would “lock” your core game account. It is not a hard process at all just click on support up top and go for it.