emergency tax

My wife works part time for company1 and earned 1400 euros this month. However she paid 798 euros in tax. Apparently she is on emergency tax.
She also works part time for company2 and has a small amount of tax credits with them.
I claim the majority of her tax credits for my fulltime salary.

She has no tax credits for company1, and until earlier this month her 20% tax rate band at 27400 was only for company2.
She requested to change the 20% tax rate band to 19400 for company2 and 8000 for company1

Yet this month she still paid tax at the high rate for company1.
She has earned for company1 this year, 5980 and has paid 1891 in tax. However 798 of that was paid this month.

When should the 20% tax rate band begin and will she be entitled to a tax refund?

If you wife was on emergency tax and now a cert of tax credit and stanard rate cut off is issued to her employer there may have been an adjustment required in April.
Tax owed at the end of April on €5,980:
Your wife has at the standard rate 8000 / 12 = 666 x 4 = 2664 x 20% = 533
Balance at the higher rate 3316 x 41% = 1360
1360 + 533 = 1893. So she has paid the correct amount of tax.
If her salary is 1400 in May 666 x 20% = 133 734 x 41% = 301
301 + 133 = 434 in tax.