THE number of consumer complaints about bike-sharing companies increased dramatically in the first half of this year.

Delays in returning deposits, poor service and systems problems topped the list, the city’s consumer rights protection commission said yesterday.

It received more than 3,700 complaints about bike rental firms — 15 times more than the same period last year.

These complaints accounted for about 5 percent of all complaints the commission received in the six months.

Problems getting deposits or balances refunded accounted for 58 percent of complaints and the inability to get through on customer service phone lines made up 28 percent.

Other issues included system problems and questionable charges, the commission said.

Shanghai has more than 1 million shared bikes, and operators should offer better service, the commission said.

The commission received a total 75,163 complaints in the first half, more than 30 percent higher than the same period a year ago.

Forty percent involved items such as home appliances, smartphones and clothing and shoes the top three.

Complaints over cross-border e-commerce platforms surged 153 percent, most of which related to cosmetics, skin care products and baby products.

“Most of these platforms are located overseas, making it difficult for consumers to have their rights protected and enjoy satisfactory after-sales service,” said Tang Jiansheng, deputy secretary-general of the Shanghai Consumer Rights Protection Commission.

Tourism, broadband and cable television, and vehicle rental topped the list of complaints about services.

Online ticketing platforms for films and amusement parks and online food delivery were other leading areas of concern.