mainline phone moved without permission

[wendyl]

My sister had her mainline telephone account with Tesco. She received a letter saying they were sorry she was leaving and advised she was not planning to Last week whilst she was away for a few days her number became unavailable and her phone showed a new number. She contacted Tesco (Friday evening on arrival home) who stated it had been moved and they did not know where and the only people who could help were OFCOM (weekdays only) She has been left unable to use her computer, with an unknown number She cannot advise her IP because she hopes to retrieve her number. She has not spoken to anyone regarding a move. The only possibility is that someone spoke to her husband (he has alzheimers and cannot recall) her account is in her own name only so should not have happened anyway I am not sure this is the right place for advice but any help in the best and quickest way to resolve would be gratefully received