Ofcom has made good on the suspicion that it was to launch an investigation into Bulldog, following widespread customer complaints over billing, poor customer service in general and network performance.

If found guilty, the ISP could face fines of over £1m.

Cable & Wireless and Bulldog have made no comment on the matter, except for a letter to its customers, in which Bulldog's Chief Executive Emanuele Angelidis admits that gaps existed in its customer service and it had experienced problems with its billing systems which resulted in erroneous bills being generated.