Complaints of slow internet and poor call quality hit Vodacom South Africa on Sunday as the mobile operator gave away free 1GB data bundles to its customers.

Vodacom, which is South Africa’s largest mobile network with over 30 million customers, launched the 1GB promotion to mark its 20 years in existence.

But the promotion has seemingly backfired in parts of the country as complaints from customers streamed in on social media about poor Vodacom network quality on Sunday.

Vodacom’s Facebook account is littered with complaints, while customers have hit out at the mobile network on Twitter.

And Vodacom customers have also complained to ITWeb Africa about the network’s poor quality on Sunday.

“Inactive network the whole day, couldn't do a ... damn thing with my phone,” Kwena Matlakeng, @MatlakengKwena on Twitter, told ITWeb Africa.

Meanwhile, others have complained about the 1GB promotion being strangled by slow internet speeds.

“What Vodacom failed to mention is that the 1GB is available at 20kbps,” ‘Gtd Sdk’, or @GtdSdk on Twitter, told ITWeb Africa.

Meanwhile, Vodacom South Africa representatives, at the time of writing, are unclear about how possible disruptions to the network came about amid the 1GB data promotion.

"We’re still busy compiling the data so it’s difficult to comment in detail at the moment about the full reach of the campaign. One thing we are quite sure of is that this was a win when it comes to bridging the digital divide and making data accessible to a much wider proportion of the population," Vodacom communications officials have told ITWeb Africa in a statement.

"There are always things to learn from trying out new ideas and taking risks. We’ll definitely be spending quite a bit of time understanding those lessons and using the information to improve services," the company added.