Yes, it can be a crime.
Section 2 of the Fraud Act 2006:
2(1) - A person is in breach of this section if he (a) dishonestly makes a
false representation, and (b) intends, by making the representation
(i) to make a gain for himself or another, or (ii) to cause loss to
another or to expose another to a risk of loss.
2(2) - A representation is false if (a) it is untrue or misleading, and
(b) the person making it knows that it is, or might be, untrue or
Note that this requires mens rea. The representation must be made dishonestly, the person making it must know that it is or might be untrue or misleading, and they must intend a gain or to cause a loss. As with Dale's answer, it is not sufficient that the trader is merely incompetent.
Some possibly relevant provisions of the Consumer Protection from Unfair Trading Regulations 2008 are:
3(1) - Unfair commercial practices are prohibited.
3(4) - A commercial practice is unfair if (a) it is a misleading
action under the provisions of regulation 5; [...] or (d) it is listed
in Schedule 1.
5(1) - A commercial practice is a misleading action if it satisfies
the conditions in either paragraph (2) or paragraph (3).
5(2) - A commercial practice satisfies the conditions of this
paragraph (a) if it contains false information and is therefore
untruthful in relation to any of the matters in paragraph (4) or if it
or its overall presentation in any way deceives or is likely to
deceive the average consumer in relation to any of the matters in that
paragraph, even if the information is factually correct; and (b) it
causes or is likely to cause the average consumer to take a
transactional decision he would not have taken otherwise.
5(4) - The matters referred to in paragraph (2)(a) are (a) the
existence or nature of the product; (b) the main characteristics of
the product (as defined in paragraph 5); (c) the extent of the
trader’s commitments; (d) the motives for the commercial practice; (e)
the nature of the sales process; [...]
5(5) In paragraph (4)(b), the “main characteristics of the product”
include (a) availability of the product; [...]
Schedule 1, paragraph 5 - Making an invitation to purchase products at
a specified price without disclosing the existence of any reasonable
grounds the trader may have for believing that he will not be able to
offer for supply, or to procure another trader to supply, those
products or equivalent products at that price for a period that is,
and in quantities that are, reasonable having regard to the product,
the scale of advertising of the product and the price offered (bait
9 - A trader is guilty of an offence if he engages in a commercial
practice which is a misleading action under regulation 5 otherwise
than by reason of the commercial practice satisfying the condition in
12 - A trader is guilty of an offence if he engages in a commercial
practice set out in any of paragraphs 1 to 10, 12 to 27 and 29 to 31
of Schedule 1.
Note that unlike fraud, there is no need to establish mens rea in the case of misleading actions. It is sufficient that the commercial practice "is likely to deceive". However, the offence listed in paragraph 5 of schedule 1 does require mens rea ("...reasonable grounds the trader may have for believing that he will not be able to...").