Customers who were charged £6 for ringing Yorkshire Water have been offered a refund.
It comes after the water firm contacted the Phone-Paid Service Authority (PSA), after receiving a complaint from a customer.
The PSA upheld YW's complaint after finding a website quoting premium-rate numbers for customers to call the company.
The official number is a local rate 0345 number, but some customers were unwittingly using the call connection service and being charged £6 per connection.
The PSA cited four breaches relating to call connection services operating on the number range 0901 545* and 09011 506* provided by London-based Caller Support Limited.
The firm has agreed to provide refunds to consumers who make a valid claim.
Customers may be asked to provide a copy of a phone bill highlighting the relevant premium rate charges before a refund is issued.
The PSA said: "Given the nature of the breaches, the PSA has taken the decision to deal with this matter using our informal procedure and allow the provider to rectify the issues raised.
"The PSA is satisfied the provider has now rectified these issues and the service is operating compliantly.’
A spokesperson from Yorkshire Water said: “We are pleased with this outcome.
"We have lots of free ways that our customers can contact us via our website. They can use live chat, request a free call back with a precise 10 minute slot that suits them, or they can talk to us via Twitter and Facebook.
"If they do need to phone us, we have a local rate 0345 number to use.
“We object to these call connection service charges for a simple phone call to us which can be made direct to us and charged at a local rate."
In April 2017, the PSA issued a £645,000 fine to a similar call connection company called DK Call which charged customers £3.60 per minute to call well-known organisations such as Sky and HMRC.
How to make a claim:
Tel: 0800 049 9877
Postal Claims: Caller Support Limited, Level 3, 207 Regent Street, London, W1B 3HH