Last year, Laemgate seafood restaurant launched a pay-in-advance food promotion online.

Up to 20,000 people purchased 50 million Thai baht (£1.2m; $1.6m) worth of vouchers, said broadcaster Thai PBS.

But the company later said it could not keep up with demand and shut down the restaurant.

Apichart Bowornbancharak and Prapassorn Bowornbancha were arrested after hundreds of people complained. 

It is not uncommon for those found guilty of fraud in Thailand to be sentenced to such long terms, owing to the number of complaints received.

However, Thai law limits jail time for public fraud to 20 years.

A food promotion gone wrong

The Laemgate seafood restaurant had last year begun selling various food vouchers that required customers to pay in advance.

One such deal offered a seafood meal at 880 baht (£22; $28) for 10 people - far cheaper than their usual prices.

Initially, those who bought the vouchers were able to claim their meals at the restaurant but a long waiting list meant an advance booking of up to several months, according to Thai PBS.

But by March, the company - Laemgate Infinite - announced its closure, claiming that it could not get hold of enough seafood to meet the demand.

It offered to refund customers who had bought vouchers, according to Thai PBS. About 375 out of 818 customers who complained got their money back.

Hundreds later filed complaints against the company and its co-owners for fraud.

Apichart Bowornbancharak and Prapassorn Bowornbancha were arrested on charges including defrauding the public through false messages.

They were found guilty on 723 counts on Wednesday and sentenced to 1,446 years in jail each.

They pleaded guilty and their sentences were cut by half to 723 years each. They will in fact only be serving a maximum of 20 years.

Their company, Laemgate Infinite, was also fined 1.8m baht, and the co-owners and the company was ordered to refund 2.5m baht in damages to the victims.

In 2017, a Thai court sentenced a fraudster to more than 13,000 years in prison. BBC