BT Wholesale appears to have upset a number of the UK's internet service providers as a result of the changes it has made to its Special Fault Investigations (SFI).
Currently, only the final clear code is charged after several SFIs are carried out on a BT Wholesale broadband or telephone line.
According to ISPreview, however, new rules which would mean that all SFIs could be charged, impacting upon both providers and end-users.
Simon Davies, Director of IDNet, told the site: "It means we'll have to dispute more and more SFI charges, which increases our admin.
"It's also wrong of BT to reject any disputes that are older than 30 days after their invoice as often the case hasn't been fully resolved by then."
Mr Davies went on to say that the changes create "an issue with engineer veracity".
However, BT has spoken out against the suggestions and said that its wholesale division would not behave in an unfair manner.
A spokesperson commented: "BT Wholesale continues to invest tools and techniques to improve broadband performance further and simplify the broadband experience."