The energy watchdog has launched an investigation into UK gas and electricity supplier Iresa over its treatment of customers.
Ofgem will look into the Nottingham-based firm's customer service processes to determine whether it treated customers fairly in their call-handling and complaints process.
It will also examine whether Iresa gave sufficient notice to customers facing financial difficulty that debt repayments were being taken out of their respective accounts.
The probe comes after Iresa's practices prompted a raft of complaints, collected by the likes of Ofgem and Citizens Advice.
Ofgem stressed that the launch of the investigation itself does not imply that it has made any findings over non-compliance.
Iresa was founded by director Adeniyi Oladeji and granted its gas and electricity supply licenses in mid-2014 with an aim to create its "own proprietary technology" to cut out third parties, lower costs and offer cheaper bills to consumers, according to its website.
A number of Iresa customers were recently caught by surprise over direct debit increases and one-off payments worth hundreds of pounds, a report by consumer publication Which? said.
It said customers were told they would have to make the extra payments within just days of receiving emails near the end of January, citing at least one complaint over a £600 one-off charge.
Others were struggling to get in touch with the company, being placed in long phone queues.
Iresa stopped taking new customers temporarily last spring after Ofgem found that customers were having trouble getting in touch with the energy provider.