Cryptocurrency trading giants Coinbase, eToro and Luno were among a gaggle of virtual asset industry participants to receive a warning from the U.K.’s Advertising Standards Authority (ASA) for promotions that were misleading about the risk associated with such investments.

The firms were criticized for “irresponsibly taking advantage of consumers’ inexperience and for failing to illustrate the risk” of investing in cryptocurrencies.

Crypto firms have caused consternation at regulatory bodies in the U.K. before, including the Financial Conduct Authority, following advertising campaigns involving Transport for London, for example. Such promotions usually accompany a spike in the price of crypto tokens.

Other companies censured include pizza chain Papa John’s, which in May offered to give away £10 ($13) in bitcoin with orders over a certain amount. In response, the company said it has a long-running association with cryptocurrency, dating back to May 2010 when it was believed that bitcoin had been first used to buy two Papa John’s pizzas.

“In that context, and when there was high customer interest in pizza and bitcoin, they [Papa John’s] ran the promotion to raise awareness of the connection between cryptocurrency and pizza,” said the firm’s response.

Kraken, CoinBurp and Exmo Exchange were also mentioned. Luno is owned by DCG, the parent company of CoinDesk.

UPDATE (Dec. 15, 12:29 UTC): Fixes Papa John’s name in fourth paragraph.