By the end of next month, parents of children taking the school bus will have their payments to 22 school bus operators insured against the businesses closing down suddenly.

The protection follows the launch of a joint accreditation scheme yesterday by the Consumers Association of Singapore (Case) and the Singapore School Transport Association (SSTA).

The scheme requires the bus operators to buy a $300,000 performance guarantee bond to insure consumers' payments against them closing shop unexpectedly.

Currently, 22 SSTA members are seeking accreditation. They provide bus services to more than half of Singapore's primary schools.

SSTA chairman Wong Ann Lin hopes more will come on board as 22 is "a bit low" when the association has about 900 members.

Case and SSTA began work on the scheme in 2015, when some operators suddenly ceased business.

In January 2015, a transport service provider for Bethesda (Bedok-Tampines) Kindergarten terminated its services abruptly, affecting 70 of the school's 200 pupils.

That same month, the owner of Sindoz Group stopped responding to phone calls after collecting at least $50,000 in bus fees from parents whose children attended five schools.

Case said: "Parents who made advance payment for up to two months of bus services were unable to seek a refund as the operator had ceased operations."

From 2010 to 2014, Case received 39 complaints against these operators. Ten of them involved operators suddenly terminating their services or collecting deposits and not providing the service.

Apart from insuring parents' payments against business closure, the scheme also requires the bus operators to send their staff for 40 hours of training over two years.

The operators also have to clearly document policies on service charges, termination and refund, as well as attend Case mediation in a consumer dispute.

Mr Wong said the scheme signifies the industry's willingness to provide better service.

"The accreditation will also instil greater confidence among SSTA members, schools, parents and the public, as well as uplift the association's professional status and leadership in the school transport industry," he added.

Ms Betty Ho, 39, who works in product development, pays $180 a month for the school bus to take her five-year-old son home from kindergarten.

"It's not just about the money. There is also the inconvenience (if the bus operator closes shop). I hope more operators sign up," she said.