The Consumer Council received 84 complaints last year about 5G services, and there were 27 gripes in the first four months of this year.

That was more than double the number of cases in the corresponding period last year, when there were 12.

Given that the 5G network is still being developed, its stability and performance might vary, the watchdog reminded people.

In one complaint, a man who lives in a remote area was persuaded to subscribe to a HK$198 per month 5G service plan from a company. Considering where he lived, the man doubted the company's 5G network could cover his residence, but signed a contract after he was assured there would be a good signal at his home.

He subsequently discovered he could only use his smartphone to access the 5G network there - and that was at a very slow speed.

Although the network speed could reach 300 to 400 megabits per second in a downtown area, the internet speed at his home was often 1Mbps, meaning a 1MB file took eight seconds to download. A 6MB song would take 48 seconds to download.

It was much faster to access the internet using another service provider's 4G network than the company's 5G one, he said.

The user then decided to terminate the contract, but was told he would have to pay HK$4,554 for the remainder of the two-year contract. He sought the council's help in negotiating an unconditional termination of the deal.

The company argued that network performance at individual indoor locations could be affected by various factors, but later canceled the contract and adjusted the fees.

In another case, a woman extended her contract with another company until 2023 and received a HK$4,500 e-coupon for the extension. She then used the coupon to buy a HK$6,000 tablet.

About three months later, the mobile network at her home became so unstable that sometimes, she could not even receive calls.

The telecom company said it was due to a system update of the 5G network in Kowloon East and that the issues could not be resolved in a short time.

After intervention by the council, the company agreed to a cancellation of the contract and waived an early termination fee, but demanded the woman repay HK$4,500 for the e-coupon.

The watchdog reminded consumers to ask about 5G network coverage before taking a subscription and to ensure mobile devices and service plans are compatible with 5G.