Also, I am not a lawyer, but the latest updates to the Trade Descriptions Ordinance (Chapter 362) are quite plainly stated, albeit a bit poorly formatted. I trust your lawyer is competent, but in order to save him/her time, I would point them here:
http://www.legislation.gov.hk/blis_pdf.nsf/4f0db701c6c25d4a4825755c00352e35/620C44C5887E4501482575EE0071B7D7/$FILE/CAP_362_e_b5.pdf
Relevant sections:
Section 12 (relevant to the scenario of them continuing to ship the Prospero X-3's):
(1) A person must not import or export any goods to which a false trade description or forged trade mark is applied. (Amended 35 of 2000 s. 98; 25 of 2012 s. 10)
Section 13H (relevant to them not delivering within a reasonable time):
(1) A trader who engages in relation to a consumer in a commercial practice that constitutes a bait and switch commits an offence.
(2) The making by a trader of an invitation to purchase a product at a specified price is a bait and switch if, having made the invitation, the trader then, with the intention of promoting a different product
-(a) refuses to show or demonstrate the product to consumers;
-(b) refuses to take orders for the product or deliver it within a reasonable time; or
-(c) shows or demonstrates a defective sample of the product.
Section 13I (relevant to them not delivering as well as the fact that the specs for the X-3's have changed since they were advertised):
(1) A trader who engages in relation to a consumer in a commercial practice that constitutes wrongly accepting payment for a product commits an offence.
(2) A trader wrongly accepts payment for a product if the trader accepts payment or other consideration for the product and at the time of that acceptance
-(a) the trader intends not to supply the product;
-(b) the trader intends to supply a product that is materially different from the product in respect of which the payment or other consideration is accepted; or
-(c) there are no reasonable grounds for believing that the trader will be able to supply the product
--(i) within the period specified by the trader at or before the time at which the payment or other consideration is accepted; or
--(ii) if no period is specified at or before that time, within a reasonable period.
From my perspective, this is a slam dunk case for many reasons so long as it makes it to a courtroom.