Johannesburg - Ahead of the Regulation of Interception of Communication Act (Rica) deadline later on Thursday, mobile operator Vodacom Group [JSE:VOD] has apologised via Twitter for difficulties "certain customers" were having calling or sending text messages on its network. The group tweeted: "We're aware that certain customers are experiencing an inability to call or SMS. Sincere apologies, we're working on a fix." On Wednesday, the group also confirmed that it was having trouble with its network. "We can confirm that a small percentage of our customers have experienced a delay in using our USSD recharge system. The airtime has been credited but in some cases it is not yet reflecting on the individual's balance. "We would like to apologise to any affected customers and assure them that their recharge will be visible on their account shortly," Vodacom's executive head of media relations Richard Boorman told I-Net Bridge. Sim cards not registered ahead of the deadline on Thursday midnight would be cut off, the operators stressed. Operators confirmed that they were expecting a last-minute rush to register as 2.7 million sim cards still need to be registered. Vodacom could not be reached at the time of writing.