Widows occupational pension.

I have had a battle with my late wife's pension scheme / employers to get the correct amount of pension paid. Fortunately I was able to scan all the letters which were issued to her and the letter stating I will be entitled to half her pension.
The correct figures have now been confirmed and 8 months arrears amounting to £3,000 will be paid at the end of November.
Fortunately I have known my late wife since the age of 12 so I knew the exact day she started working for the company and I knew the amount of AVC'S she paid.
Has anybody had a situation where ex employers have tried to pay too much pension?.
I am wondering if employers try it on and hopes a widow / widower will not know their late husband's / wife's pension rights.

Frank