An EE customer was told to pay a mobile bill of £86 for calls made to her T-Mobile voicemail service while she was on holiday in the Dominican Republic.
Daisy Isham, 24, from Hertfordshire, received a string of marketing calls from withheld numbers during the first few days of her trip.
She ignored the incoming calls before turning her phone off, reports the Telegraph.
When Ms Isham returned home, EE - the UK parent company of T-Mobile - issued her with the bill, saying she was liable to pay because the calls had connected to her voicemail.
"I have repeatedly tried to remove my number from these automated call lists," Ms Isham stated.
"I’ve blocked some numbers and even asked T?Mobile to block all withheld numbers, but to no avail. EE says it is my fault and that I have to pay the bill."
EE offered to pay 50 per cent of the bill as a "goodwill gesture", but after seeking advice from Ofcom and dispute resolution service Cisas, the complainant asked for a full explanation from her operator.
EE said it would cost £15 to send the letter, which could take up to 40 days to arrive. The firm refused to provide the names of the customer service advisers who spoke to Ms Isham.
"The service that I have received from EE’s customer service department has been absolutely disgusting," she stated.
"I was hung up on five times and promised call backs from managers on a number of occasions, but this never happened."
Ms Isham was told that unless she paid the full bill, debt collectors would be sent to her house.
The Telegraph reports that when it approached EE about Ms Isham's case, it was told she would have to pay the bill. An EE spokesperson said the only way to avoid being charged for calls while abroad is to disable a phone’s voicemail facility.
A few days later, EE contacted Ms Isham confirming that the full debt was being wiped.
Ernest Doku, telecoms expert at uSwitch.com, explained that EE is one of few service providers to charge customers when a call is directed to voicemail when they are overseas.
He explained that O2 and Three do not issue charges, while Vodafone is less clear about its billing rules.