Lynn Humphrys, pictured, joined CT Plus in July 2013 on a minimum 32-hour a week contract.
Later that was increased to a minimum 40 hours a week, but as the hours increased, Miss Humphrys said she was struggling with pain.
She claims a letter from her doctor – stating she must not work more than 44 hours a week because she suffered from fibromyalgia – was ignored.
'I felt discriminated against,' she said.
The final straw was a twelve-and-three-quarter-hour shift on an upcoming timetable.
She resigned in October and is now claiming constructive dismissal.
But CT Plus operations manager Lee Murphy said the company worked hard to give Miss Humphrys flexible hours to help accommodate her condition.
