BT has claimed there has been a 55% increase in the amount of complaints it has received from customers about mis-selling - which totals more than 11,000 complaints about the problem last month.
BT Retail chief executive Pierre Danon said the problem was "spiralling out of control" and that it was damaging the reputation of the industry.
According to BT, complaints about mis-selling include new market entrants that tell customers they work for BT, or have done a deal with BT to give consumers cheaper calls, when no such offer has been agreed.
BT was itself rapped by Oftel last month for marketing directly to customers who had decided to switch to another telecoms provider.
Oftel threatened to fine the telecoms giant. BT is appealing against the ruling (Marketing, November 13).
Ofcom and Oftel are investigating BT's complaints.