Complaints about prepaid crab coupons are on the rise in Shanghai, Jiefang Daily reported on Wednesday.

In one example, Dong, a resident in Shanghai, received an order of crabs short of the agreed weight with a prepaid coupon for 1,088 yuan ($180) after the National Day Holiday. Still worse, several crabs were dead.

A woman surnamed Ma was even more unlucky. She and her friends have prepaid coupons with a face value of 898 and 1,198 yuan from a company selling crabs. The coupons are valid for two years. But the company can't be found.

After buyers filed a complaint to the local consumers' association, it found the company had gone bankrupt.